diff --git a/Fabric.Backend.Center/src/app.module.ts b/Fabric.Backend.Center/src/app.module.ts
index b512491..4a34b35 100644
--- a/Fabric.Backend.Center/src/app.module.ts
+++ b/Fabric.Backend.Center/src/app.module.ts
@@ -4,9 +4,15 @@ import { buildTypeOrmConfig } from './database.config';
 import { HealthController } from './common/health.controller';
 import { AuthModule } from './auth/auth.module';
 import { NodesModule } from './nodes/nodes.module';
+import { AuditModule } from './audit/audit.module';
 
 @Module({
-  imports: [TypeOrmModule.forRoot(buildTypeOrmConfig()), AuthModule, NodesModule],
+  imports: [
+    TypeOrmModule.forRoot(buildTypeOrmConfig()),
+    AuditModule,
+    AuthModule,
+    NodesModule,
+  ],
   controllers: [HealthController],
 })
 export class AppModule {}
diff --git a/Fabric.Backend.Center/src/audit/audit.module.ts b/Fabric.Backend.Center/src/audit/audit.module.ts
new file mode 100644
index 0000000..d87290a
--- /dev/null
+++ b/Fabric.Backend.Center/src/audit/audit.module.ts
@@ -0,0 +1,12 @@
+import { Global, Module } from '@nestjs/common';
+import { TypeOrmModule } from '@nestjs/typeorm';
+import { AuditLog } from '../entities/audit-log.entity';
+import { AuditService } from './audit.service';
+
+@Global()
+@Module({
+  imports: [TypeOrmModule.forFeature([AuditLog])],
+  providers: [AuditService],
+  exports: [AuditService],
+})
+export class AuditModule {}
diff --git a/Fabric.Backend.Center/src/audit/audit.service.ts b/Fabric.Backend.Center/src/audit/audit.service.ts
new file mode 100644
index 0000000..c90d0e9
--- /dev/null
+++ b/Fabric.Backend.Center/src/audit/audit.service.ts
@@ -0,0 +1,31 @@
+import { Injectable } from '@nestjs/common';
+import { InjectRepository } from '@nestjs/typeorm';
+import { Repository } from 'typeorm';
+import { AuditLog } from '../entities/audit-log.entity';
+
+export type AuditWriteInput = {
+  action: string;
+  actorId?: string | null;
+  targetType?: string | null;
+  targetId?: string | null;
+  detail?: string | null;
+};
+
+@Injectable()
+export class AuditService {
+  constructor(
+    @InjectRepository(AuditLog)
+    private readonly auditRepo: Repository<AuditLog>,
+  ) {}
+
+  async write(input: AuditWriteInput): Promise<void> {
+    const row = this.auditRepo.create({
+      action: input.action,
+      actorId: input.actorId ?? null,
+      targetType: input.targetType ?? null,
+      targetId: input.targetId ?? null,
+      detail: input.detail ?? null,
+    });
+    await this.auditRepo.save(row);
+  }
+}
diff --git a/Fabric.Backend.Center/src/auth/auth.service.ts b/Fabric.Backend.Center/src/auth/auth.service.ts
index e228609..1923a67 100644
--- a/Fabric.Backend.Center/src/auth/auth.service.ts
+++ b/Fabric.Backend.Center/src/auth/auth.service.ts
@@ -10,6 +10,7 @@ import * as jwt from 'jsonwebtoken';
 import { User } from '../entities/user.entity';
 import { RegisterDto } from './dto.register.dto';
 import { LoginDto } from './dto.login.dto';
+import { AuditService } from '../audit/audit.service';
 
 function parseDurationToSeconds(input: string, fallbackSeconds: number): number {
   const raw = input.trim();
@@ -44,6 +45,7 @@ export class AuthService {
   constructor(
     @InjectRepository(User)
     private readonly userRepo: Repository<User>,
+    private readonly audit: AuditService,
   ) {}
 
   async register(input: RegisterDto) {
@@ -60,6 +62,14 @@ export class AuthService {
     });
     const saved = await this.userRepo.save(user);
 
+    await this.audit.write({
+      action: 'auth.register',
+      actorId: saved.id,
+      targetType: 'user',
+      targetId: saved.id,
+      detail: JSON.stringify({ email: saved.email }),
+    });
+
     return {
       id: saved.id,
       email: saved.email,
@@ -79,6 +89,14 @@ export class AuthService {
     user.refreshTokenHash = await bcrypt.hash(refreshToken, 10);
     await this.userRepo.save(user);
 
+    await this.audit.write({
+      action: 'auth.login',
+      actorId: user.id,
+      targetType: 'user',
+      targetId: user.id,
+      detail: JSON.stringify({ email: user.email }),
+    });
+
     return {
       accessToken,
       refreshToken,
@@ -112,6 +130,14 @@ export class AuthService {
     user.refreshTokenHash = await bcrypt.hash(newRefreshToken, 10);
     await this.userRepo.save(user);
 
+    await this.audit.write({
+      action: 'auth.refresh',
+      actorId: user.id,
+      targetType: 'user',
+      targetId: user.id,
+      detail: null,
+    });
+
     return {
       accessToken: newAccessToken,
       refreshToken: newRefreshToken,
@@ -135,6 +161,13 @@ export class AuthService {
 
     user.refreshTokenHash = null;
     await this.userRepo.save(user);
+    await this.audit.write({
+      action: 'auth.logout',
+      actorId: user.id,
+      targetType: 'user',
+      targetId: user.id,
+      detail: null,
+    });
     return { status: 'ok' };
   }
 }
diff --git a/Fabric.Backend.Center/src/database.config.ts b/Fabric.Backend.Center/src/database.config.ts
index 52699ba..7e285df 100644
--- a/Fabric.Backend.Center/src/database.config.ts
+++ b/Fabric.Backend.Center/src/database.config.ts
@@ -1,6 +1,7 @@
 import { TypeOrmModuleOptions } from '@nestjs/typeorm';
 import { User } from './entities/user.entity';
 import { GuildNode } from './entities/guild-node.entity';
+import { AuditLog } from './entities/audit-log.entity';
 
 export const buildTypeOrmConfig = (): TypeOrmModuleOptions => ({
   type: 'mysql',
@@ -9,7 +10,7 @@ export const buildTypeOrmConfig = (): TypeOrmModuleOptions => ({
   username: process.env.DB_USER ?? 'fabric',
   password: process.env.DB_PASSWORD ?? 'fabric',
   database: process.env.DB_NAME ?? 'fabric_center',
-  entities: [User, GuildNode],
+  entities: [User, GuildNode, AuditLog],
   synchronize: (process.env.DB_SYNC ?? 'true') === 'true',
   logging: (process.env.DB_LOGGING ?? 'false') === 'true',
 });
diff --git a/Fabric.Backend.Center/src/entities/audit-log.entity.ts b/Fabric.Backend.Center/src/entities/audit-log.entity.ts
new file mode 100644
index 0000000..0c273d0
--- /dev/null
+++ b/Fabric.Backend.Center/src/entities/audit-log.entity.ts
@@ -0,0 +1,25 @@
+import { Column, CreateDateColumn, Entity, PrimaryGeneratedColumn } from 'typeorm';
+
+@Entity('audit_logs')
+export class AuditLog {
+  @PrimaryGeneratedColumn('uuid')
+  id!: string;
+
+  @Column()
+  action!: string;
+
+  @Column({ nullable: true })
+  actorId!: string | null;
+
+  @Column({ nullable: true })
+  targetType!: string | null;
+
+  @Column({ nullable: true })
+  targetId!: string | null;
+
+  @Column({ type: 'text', nullable: true })
+  detail!: string | null;
+
+  @CreateDateColumn()
+  createdAt!: Date;
+}
diff --git a/Fabric.Backend.Center/src/nodes/nodes.controller.ts b/Fabric.Backend.Center/src/nodes/nodes.controller.ts
index 9bd9487..c126d92 100644
--- a/Fabric.Backend.Center/src/nodes/nodes.controller.ts
+++ b/Fabric.Backend.Center/src/nodes/nodes.controller.ts
@@ -15,6 +15,7 @@ import {
 import { InjectRepository } from '@nestjs/typeorm';
 import { Repository } from 'typeorm';
 import { GuildNode } from '../entities/guild-node.entity';
+import { AuditService } from '../audit/audit.service';
 import { RegisterNodeDto } from './dto.register-node.dto';
 import { UpdateNodeStatusDto } from './dto.update-node-status.dto';
 
@@ -23,6 +24,7 @@ export class NodesController {
   constructor(
     @InjectRepository(GuildNode)
     private readonly nodeRepo: Repository<GuildNode>,
+    private readonly audit: AuditService,
   ) {}
 
   @Post('register')
@@ -52,6 +54,12 @@ export class NodesController {
       status: 'active',
     });
     const saved = await this.nodeRepo.save(node);
+    await this.audit.write({
+      action: 'node.register',
+      targetType: 'node',
+      targetId: saved.nodeId,
+      detail: JSON.stringify({ endpoint: saved.endpoint }),
+    });
 
     return {
       status: 'accepted',
@@ -78,6 +86,12 @@ export class NodesController {
     }
 
     const saved = await this.nodeRepo.save(node);
+    await this.audit.write({
+      action: 'node.heartbeat',
+      targetType: 'node',
+      targetId: saved.nodeId,
+      detail: JSON.stringify({ status: saved.status }),
+    });
     return {
       status: 'ok',
       nodeId: saved.nodeId,
@@ -98,6 +112,12 @@ export class NodesController {
 
     node.status = body.status;
     const saved = await this.nodeRepo.save(node);
+    await this.audit.write({
+      action: 'node.status.update',
+      targetType: 'node',
+      targetId: saved.nodeId,
+      detail: JSON.stringify({ status: saved.status }),
+    });
     return {
       id: saved.id,
       nodeId: saved.nodeId,
diff --git a/docs/TODO-backend-center-guild.md b/docs/TODO-backend-center-guild.md
index 8b48e70..8975e91 100644
--- a/docs/TODO-backend-center-guild.md
+++ b/docs/TODO-backend-center-guild.md
@@ -30,7 +30,7 @@
 - [x] node 心跳接口（可选）
 
 ### 1.3 Center 运维能力
-- [ ] 审计日志（auth/node 关键操作）
+- [x] 审计日志（auth/node 关键操作）
 - [ ] 健康检查深化（DB ready）
 - [x] 配置校验（启动时必填项检查）