diff --git a/crates/erp-auth/src/service/mod.rs b/crates/erp-auth/src/service/mod.rs
index ed40a5b..b0392f3 100644
--- a/crates/erp-auth/src/service/mod.rs
+++ b/crates/erp-auth/src/service/mod.rs
@@ -1,4 +1,5 @@
 pub mod auth_service;
 pub mod password;
+pub mod seed;
 pub mod token_service;
 pub mod user_service;
diff --git a/crates/erp-auth/src/service/seed.rs b/crates/erp-auth/src/service/seed.rs
new file mode 100644
index 0000000..8c6b878
--- /dev/null
+++ b/crates/erp-auth/src/service/seed.rs
@@ -0,0 +1,265 @@
+use sea_orm::{ActiveModelTrait, Set};
+use uuid::Uuid;
+
+use crate::entity::{permission, role, role_permission, user, user_credential, user_role};
+use crate::error::AuthError;
+
+use super::password;
+
+/// Permission definitions to seed for every new tenant.
+/// Each tuple is: (code, name, resource, action, description)
+const DEFAULT_PERMISSIONS: &[(&str, &str, &str, &str, &str)] = &[
+    ("user:create", "创建用户", "user", "create", "创建新用户"),
+    ("user:read", "查看用户", "user", "read", "查看用户信息"),
+    ("user:update", "编辑用户", "user", "update", "编辑用户信息"),
+    ("user:delete", "删除用户", "user", "delete", "软删除用户"),
+    ("role:create", "创建角色", "role", "create", "创建新角色"),
+    ("role:read", "查看角色", "role", "read", "查看角色信息"),
+    ("role:update", "编辑角色", "role", "update", "编辑角色"),
+    ("role:delete", "删除角色", "role", "delete", "删除角色"),
+    (
+        "permission:read",
+        "查看权限",
+        "permission",
+        "read",
+        "查看权限列表",
+    ),
+    (
+        "organization:create",
+        "创建组织",
+        "organization",
+        "create",
+        "创建组织",
+    ),
+    (
+        "organization:read",
+        "查看组织",
+        "organization",
+        "read",
+        "查看组织架构",
+    ),
+    (
+        "organization:update",
+        "编辑组织",
+        "organization",
+        "update",
+        "编辑组织",
+    ),
+    (
+        "organization:delete",
+        "删除组织",
+        "organization",
+        "delete",
+        "删除组织",
+    ),
+    (
+        "department:create",
+        "创建部门",
+        "department",
+        "create",
+        "创建部门",
+    ),
+    (
+        "department:read",
+        "查看部门",
+        "department",
+        "read",
+        "查看部门",
+    ),
+    (
+        "department:update",
+        "编辑部门",
+        "department",
+        "update",
+        "编辑部门",
+    ),
+    (
+        "department:delete",
+        "删除部门",
+        "department",
+        "delete",
+        "删除部门",
+    ),
+    ("position:create", "创建岗位", "position", "create", "创建岗位"),
+    ("position:read", "查看岗位", "position", "read", "查看岗位"),
+    ("position:update", "编辑岗位", "position", "update", "编辑岗位"),
+    ("position:delete", "删除岗位", "position", "delete", "删除岗位"),
+];
+
+/// Indices of read-only permissions within DEFAULT_PERMISSIONS.
+const READ_PERM_INDICES: &[usize] = &[1, 5, 9, 11, 15, 19];
+
+/// Seed default auth data for a new tenant.
+///
+/// Creates:
+/// - 21 permissions covering user/role/permission/organization/department/position CRUD
+/// - An "admin" system role with all permissions
+/// - A "viewer" system role with read-only permissions
+/// - A super-admin user with the admin role and a password credential
+pub async fn seed_tenant_auth(
+    db: &sea_orm::DatabaseConnection,
+    tenant_id: Uuid,
+    super_admin_password: &str,
+) -> Result<(), AuthError> {
+    let now = chrono::Utc::now();
+    let system_user_id = Uuid::nil();
+
+    // 1. Create permissions
+    let mut perm_ids: Vec<Uuid> = Vec::with_capacity(DEFAULT_PERMISSIONS.len());
+    for (code, name, resource, action, desc) in DEFAULT_PERMISSIONS {
+        let perm_id = Uuid::now_v7();
+        perm_ids.push(perm_id);
+
+        let perm = permission::ActiveModel {
+            id: Set(perm_id),
+            tenant_id: Set(tenant_id),
+            code: Set(code.to_string()),
+            name: Set(name.to_string()),
+            resource: Set(resource.to_string()),
+            action: Set(action.to_string()),
+            description: Set(Some(desc.to_string())),
+            created_at: Set(now),
+            updated_at: Set(now),
+            created_by: Set(system_user_id),
+            updated_by: Set(system_user_id),
+            deleted_at: Set(None),
+            version: Set(1),
+        };
+        perm.insert(db).await.map_err(|e| AuthError::Validation(e.to_string()))?;
+    }
+
+    // 2. Create "admin" role with all permissions
+    let admin_role_id = Uuid::now_v7();
+    let admin_role = role::ActiveModel {
+        id: Set(admin_role_id),
+        tenant_id: Set(tenant_id),
+        name: Set("管理员".to_string()),
+        code: Set("admin".to_string()),
+        description: Set(Some("系统管理员，拥有所有权限".to_string())),
+        is_system: Set(true),
+        created_at: Set(now),
+        updated_at: Set(now),
+        created_by: Set(system_user_id),
+        updated_by: Set(system_user_id),
+        deleted_at: Set(None),
+        version: Set(1),
+    };
+    admin_role.insert(db).await.map_err(|e| AuthError::Validation(e.to_string()))?;
+
+    // Assign all permissions to admin role
+    // role_permission uses composite PK (role_id, permission_id) -- no separate id column
+    for perm_id in &perm_ids {
+        let rp = role_permission::ActiveModel {
+            role_id: Set(admin_role_id),
+            permission_id: Set(*perm_id),
+            tenant_id: Set(tenant_id),
+            created_at: Set(now),
+            updated_at: Set(now),
+            created_by: Set(system_user_id),
+            updated_by: Set(system_user_id),
+            deleted_at: Set(None),
+            version: Set(1),
+        };
+        rp.insert(db).await.map_err(|e| AuthError::Validation(e.to_string()))?;
+    }
+
+    // 3. Create "viewer" role with read-only permissions
+    let viewer_role_id = Uuid::now_v7();
+    let viewer_role = role::ActiveModel {
+        id: Set(viewer_role_id),
+        tenant_id: Set(tenant_id),
+        name: Set("查看者".to_string()),
+        code: Set("viewer".to_string()),
+        description: Set(Some("只读用户，可查看所有数据".to_string())),
+        is_system: Set(true),
+        created_at: Set(now),
+        updated_at: Set(now),
+        created_by: Set(system_user_id),
+        updated_by: Set(system_user_id),
+        deleted_at: Set(None),
+        version: Set(1),
+    };
+    viewer_role.insert(db).await.map_err(|e| AuthError::Validation(e.to_string()))?;
+
+    // Assign read permissions to viewer role
+    for idx in READ_PERM_INDICES {
+        if *idx < perm_ids.len() {
+            let rp = role_permission::ActiveModel {
+                role_id: Set(viewer_role_id),
+                permission_id: Set(perm_ids[*idx]),
+                tenant_id: Set(tenant_id),
+                created_at: Set(now),
+                updated_at: Set(now),
+                created_by: Set(system_user_id),
+                updated_by: Set(system_user_id),
+                deleted_at: Set(None),
+                version: Set(1),
+            };
+            rp.insert(db).await.map_err(|e| AuthError::Validation(e.to_string()))?;
+        }
+    }
+
+    // 4. Create super admin user
+    let admin_user_id = Uuid::now_v7();
+    let password_hash = password::hash_password(super_admin_password)?;
+
+    let admin_user = user::ActiveModel {
+        id: Set(admin_user_id),
+        tenant_id: Set(tenant_id),
+        username: Set("admin".to_string()),
+        email: Set(None),
+        phone: Set(None),
+        display_name: Set(Some("系统管理员".to_string())),
+        avatar_url: Set(None),
+        status: Set("active".to_string()),
+        last_login_at: Set(None),
+        created_at: Set(now),
+        updated_at: Set(now),
+        created_by: Set(system_user_id),
+        updated_by: Set(system_user_id),
+        deleted_at: Set(None),
+        version: Set(1),
+    };
+    admin_user.insert(db).await.map_err(|e| AuthError::Validation(e.to_string()))?;
+
+    // Create password credential for admin user
+    let cred = user_credential::ActiveModel {
+        id: Set(Uuid::now_v7()),
+        tenant_id: Set(tenant_id),
+        user_id: Set(admin_user_id),
+        credential_type: Set("password".to_string()),
+        credential_data: Set(Some(serde_json::json!({ "hash": password_hash }))),
+        verified: Set(true),
+        created_at: Set(now),
+        updated_at: Set(now),
+        created_by: Set(system_user_id),
+        updated_by: Set(system_user_id),
+        deleted_at: Set(None),
+        version: Set(1),
+    };
+    cred.insert(db).await.map_err(|e| AuthError::Validation(e.to_string()))?;
+
+    // 5. Assign admin role to admin user
+    // user_role uses composite PK (user_id, role_id) -- no separate id column
+    let user_role_assignment = user_role::ActiveModel {
+        user_id: Set(admin_user_id),
+        role_id: Set(admin_role_id),
+        tenant_id: Set(tenant_id),
+        created_at: Set(now),
+        updated_at: Set(now),
+        created_by: Set(system_user_id),
+        updated_by: Set(system_user_id),
+        deleted_at: Set(None),
+        version: Set(1),
+    };
+    user_role_assignment.insert(db).await.map_err(|e| AuthError::Validation(e.to_string()))?;
+
+    tracing::info!(
+        tenant_id = %tenant_id,
+        admin_user_id = %admin_user_id,
+        "Seeded tenant auth: admin user, 2 roles, {} permissions",
+        DEFAULT_PERMISSIONS.len()
+    );
+
+    Ok(())
+}
diff --git a/crates/erp-server/config/default.toml b/crates/erp-server/config/default.toml
index 29d8d1e..601ccec 100644
--- a/crates/erp-server/config/default.toml
+++ b/crates/erp-server/config/default.toml
@@ -15,5 +15,8 @@ secret = "change-me-in-production"
 access_token_ttl = "15m"
 refresh_token_ttl = "7d"
 
+[auth]
+super_admin_password = "Admin@2026"
+
 [log]
 level = "info"
diff --git a/crates/erp-server/src/config.rs b/crates/erp-server/src/config.rs
index be91477..bc6629e 100644
--- a/crates/erp-server/src/config.rs
+++ b/crates/erp-server/src/config.rs
@@ -6,6 +6,7 @@ pub struct AppConfig {
     pub database: DatabaseConfig,
     pub redis: RedisConfig,
     pub jwt: JwtConfig,
+    pub auth: AuthConfig,
     pub log: LogConfig,
 }
 
@@ -39,6 +40,11 @@ pub struct LogConfig {
     pub level: String,
 }
 
+#[derive(Debug, Clone, Deserialize)]
+pub struct AuthConfig {
+    pub super_admin_password: String,
+}
+
 impl AppConfig {
     pub fn load() -> anyhow::Result<Self> {
         let config = config::Config::builder()
diff --git a/crates/erp-server/src/main.rs b/crates/erp-server/src/main.rs
index 77f0c8c..e9534a8 100644
--- a/crates/erp-server/src/main.rs
+++ b/crates/erp-server/src/main.rs
@@ -13,6 +13,7 @@ use tracing_subscriber::EnvFilter;
 use erp_core::events::EventBus;
 use erp_core::module::{ErpModule, ModuleRegistry};
 use erp_server_migration::MigratorTrait;
+use sea_orm::{ConnectionTrait, FromQueryResult};
 
 #[tokio::main]
 async fn main() -> anyhow::Result<()> {
@@ -37,6 +38,58 @@ async fn main() -> anyhow::Result<()> {
     erp_server_migration::Migrator::up(&db, None).await?;
     tracing::info!("Database migrations applied");
 
+    // Seed default tenant and auth data if not present
+    {
+        #[derive(sea_orm::FromQueryResult)]
+        struct TenantId {
+            id: uuid::Uuid,
+        }
+
+        let existing = TenantId::find_by_statement(sea_orm::Statement::from_string(
+            sea_orm::DatabaseBackend::Postgres,
+            "SELECT id FROM tenants WHERE deleted_at IS NULL LIMIT 1".to_string(),
+        ))
+        .one(&db)
+        .await
+        .map_err(|e| anyhow::anyhow!("Failed to query tenants: {}", e))?;
+
+        match existing {
+            Some(row) => {
+                tracing::info!(tenant_id = %row.id, "Default tenant already exists, skipping seed");
+            }
+            None => {
+                let new_tenant_id = uuid::Uuid::now_v7();
+
+                // Insert default tenant using raw SQL (no tenant entity in erp-server)
+                db.execute(sea_orm::Statement::from_sql_and_values(
+                    sea_orm::DatabaseBackend::Postgres,
+                    "INSERT INTO tenants (id, name, code, status, created_at, updated_at) VALUES ($1, $2, $3, $4, NOW(), NOW())",
+                    [
+                        new_tenant_id.into(),
+                        "Default Tenant".into(),
+                        "default".into(),
+                        "active".into(),
+                    ],
+                ))
+                .await
+                .map_err(|e| anyhow::anyhow!("Failed to create default tenant: {}", e))?;
+
+                tracing::info!(tenant_id = %new_tenant_id, "Created default tenant");
+
+                // Seed auth data (permissions, roles, admin user)
+                erp_auth::service::seed::seed_tenant_auth(
+                    &db,
+                    new_tenant_id,
+                    &config.auth.super_admin_password,
+                )
+                .await
+                .map_err(|e| anyhow::anyhow!("Failed to seed auth data: {}", e))?;
+
+                tracing::info!(tenant_id = %new_tenant_id, "Default tenant ready with auth seed data");
+            }
+        }
+    }
+
     // Connect to Redis
     let _redis_client = redis::Client::open(&config.redis.url[..])?;
     tracing::info!("Redis client created");