diff --git a/packages/services/knowledge-service/src/migrations/AddMultiTenancyToKnowledgeService.ts b/packages/services/knowledge-service/src/migrations/AddMultiTenancyToKnowledgeService.ts
new file mode 100644
index 0000000..bc4928b
--- /dev/null
+++ b/packages/services/knowledge-service/src/migrations/AddMultiTenancyToKnowledgeService.ts
@@ -0,0 +1,125 @@
+import { MigrationInterface, QueryRunner } from 'typeorm';
+
+/**
+ * 为 knowledge-service 的四张表添加 tenant_id 列
+ *
+ * 影响的表：
+ * - user_memories
+ * - system_experiences
+ * - knowledge_articles
+ * - knowledge_chunks
+ *
+ * 使用默认租户 ID 回填现有数据
+ */
+export class AddMultiTenancyToKnowledgeService1738900100000
+  implements MigrationInterface
+{
+  name = 'AddMultiTenancyToKnowledgeService1738900100000';
+
+  private readonly DEFAULT_TENANT_ID =
+    '00000000-0000-0000-0000-000000000001';
+
+  public async up(queryRunner: QueryRunner): Promise<void> {
+    // ========== 1. user_memories 表 ==========
+    await queryRunner.query(
+      `ALTER TABLE "user_memories" ADD COLUMN IF NOT EXISTS "tenant_id" UUID`,
+    );
+    await queryRunner.query(
+      `UPDATE "user_memories" SET "tenant_id" = '${this.DEFAULT_TENANT_ID}' WHERE "tenant_id" IS NULL`,
+    );
+    await queryRunner.query(
+      `ALTER TABLE "user_memories" ALTER COLUMN "tenant_id" SET NOT NULL`,
+    );
+    await queryRunner.query(
+      `ALTER TABLE "user_memories" ALTER COLUMN "tenant_id" SET DEFAULT '${this.DEFAULT_TENANT_ID}'`,
+    );
+    await queryRunner.query(
+      `CREATE INDEX IF NOT EXISTS "idx_user_memories_tenant" ON "user_memories" ("tenant_id")`,
+    );
+
+    // ========== 2. system_experiences 表 ==========
+    await queryRunner.query(
+      `ALTER TABLE "system_experiences" ADD COLUMN IF NOT EXISTS "tenant_id" UUID`,
+    );
+    await queryRunner.query(
+      `UPDATE "system_experiences" SET "tenant_id" = '${this.DEFAULT_TENANT_ID}' WHERE "tenant_id" IS NULL`,
+    );
+    await queryRunner.query(
+      `ALTER TABLE "system_experiences" ALTER COLUMN "tenant_id" SET NOT NULL`,
+    );
+    await queryRunner.query(
+      `ALTER TABLE "system_experiences" ALTER COLUMN "tenant_id" SET DEFAULT '${this.DEFAULT_TENANT_ID}'`,
+    );
+    await queryRunner.query(
+      `CREATE INDEX IF NOT EXISTS "idx_system_experiences_tenant" ON "system_experiences" ("tenant_id")`,
+    );
+
+    // ========== 3. knowledge_articles 表 ==========
+    await queryRunner.query(
+      `ALTER TABLE "knowledge_articles" ADD COLUMN IF NOT EXISTS "tenant_id" UUID`,
+    );
+    await queryRunner.query(
+      `UPDATE "knowledge_articles" SET "tenant_id" = '${this.DEFAULT_TENANT_ID}' WHERE "tenant_id" IS NULL`,
+    );
+    await queryRunner.query(
+      `ALTER TABLE "knowledge_articles" ALTER COLUMN "tenant_id" SET NOT NULL`,
+    );
+    await queryRunner.query(
+      `ALTER TABLE "knowledge_articles" ALTER COLUMN "tenant_id" SET DEFAULT '${this.DEFAULT_TENANT_ID}'`,
+    );
+    await queryRunner.query(
+      `CREATE INDEX IF NOT EXISTS "idx_knowledge_articles_tenant" ON "knowledge_articles" ("tenant_id")`,
+    );
+
+    // ========== 4. knowledge_chunks 表 ==========
+    await queryRunner.query(
+      `ALTER TABLE "knowledge_chunks" ADD COLUMN IF NOT EXISTS "tenant_id" UUID`,
+    );
+    await queryRunner.query(
+      `UPDATE "knowledge_chunks" SET "tenant_id" = '${this.DEFAULT_TENANT_ID}' WHERE "tenant_id" IS NULL`,
+    );
+    await queryRunner.query(
+      `ALTER TABLE "knowledge_chunks" ALTER COLUMN "tenant_id" SET NOT NULL`,
+    );
+    await queryRunner.query(
+      `ALTER TABLE "knowledge_chunks" ALTER COLUMN "tenant_id" SET DEFAULT '${this.DEFAULT_TENANT_ID}'`,
+    );
+    await queryRunner.query(
+      `CREATE INDEX IF NOT EXISTS "idx_knowledge_chunks_tenant" ON "knowledge_chunks" ("tenant_id")`,
+    );
+  }
+
+  public async down(queryRunner: QueryRunner): Promise<void> {
+    // knowledge_chunks
+    await queryRunner.query(
+      `DROP INDEX IF EXISTS "idx_knowledge_chunks_tenant"`,
+    );
+    await queryRunner.query(
+      `ALTER TABLE "knowledge_chunks" DROP COLUMN IF EXISTS "tenant_id"`,
+    );
+
+    // knowledge_articles
+    await queryRunner.query(
+      `DROP INDEX IF EXISTS "idx_knowledge_articles_tenant"`,
+    );
+    await queryRunner.query(
+      `ALTER TABLE "knowledge_articles" DROP COLUMN IF EXISTS "tenant_id"`,
+    );
+
+    // system_experiences
+    await queryRunner.query(
+      `DROP INDEX IF EXISTS "idx_system_experiences_tenant"`,
+    );
+    await queryRunner.query(
+      `ALTER TABLE "system_experiences" DROP COLUMN IF EXISTS "tenant_id"`,
+    );
+
+    // user_memories
+    await queryRunner.query(
+      `DROP INDEX IF EXISTS "idx_user_memories_tenant"`,
+    );
+    await queryRunner.query(
+      `ALTER TABLE "user_memories" DROP COLUMN IF EXISTS "tenant_id"`,
+    );
+  }
+}