diff --git a/server/routers/knowledge_router.py b/server/routers/knowledge_router.py
index ae133301..16b52a3e 100644
--- a/server/routers/knowledge_router.py
+++ b/server/routers/knowledge_router.py
@@ -1130,9 +1130,9 @@ async def upload_file(
     timestamp = int(time.time() * 1000)
     minio_filename = f"{basename}_{timestamp}{ext}"
 
-    # 生成符合MinIO规范的存储桶名称（将下划线替换为连字符）
+    # 生成符合MinIO规范的存储桶名称（将下划线替换为连字符，截取长度以满足MinIO的63字符限制）
     if db_id:
-        bucket_name = f"ref-{db_id.replace('_', '-')}"
+        bucket_name = f"ref-{db_id[:32].replace('_', '-')}"
     else:
         bucket_name = "default-uploads"
 
diff --git a/src/storage/postgres/manager.py b/src/storage/postgres/manager.py
index 021394c9..a4fa9254 100644
--- a/src/storage/postgres/manager.py
+++ b/src/storage/postgres/manager.py
@@ -142,6 +142,11 @@ class PostgresManager(metaclass=SingletonMeta):
             "ALTER TABLE IF EXISTS evaluation_result_details ADD COLUMN IF NOT EXISTS generated_answer TEXT",
             "ALTER TABLE IF EXISTS evaluation_result_details ADD COLUMN IF NOT EXISTS retrieved_chunks JSONB",
             "ALTER TABLE IF EXISTS evaluation_result_details ADD COLUMN IF NOT EXISTS metrics JSONB",
+            # 扩展 db_id 字段长度以支持最长 75 字符的 ID（kb_private_ + 64字符hash）
+            "ALTER TABLE IF EXISTS knowledge_bases ALTER COLUMN db_id TYPE VARCHAR(80)",
+            "ALTER TABLE IF EXISTS knowledge_files ALTER COLUMN db_id TYPE VARCHAR(80)",
+            "ALTER TABLE IF EXISTS evaluation_benchmarks ALTER COLUMN db_id TYPE VARCHAR(80)",
+            "ALTER TABLE IF EXISTS evaluation_results ALTER COLUMN db_id TYPE VARCHAR(80)",
             "CREATE INDEX IF NOT EXISTS idx_kb_type ON knowledge_bases(kb_type)",
             "CREATE INDEX IF NOT EXISTS idx_kb_name ON knowledge_bases(name)",
             "CREATE INDEX IF NOT EXISTS idx_kf_db_id ON knowledge_files(db_id)",
diff --git a/src/storage/postgres/models_knowledge.py b/src/storage/postgres/models_knowledge.py
index 1fed512a..ffe3679f 100644
--- a/src/storage/postgres/models_knowledge.py
+++ b/src/storage/postgres/models_knowledge.py
@@ -28,7 +28,7 @@ class KnowledgeBase(Base):
     __table_args__ = (UniqueConstraint("db_id", name="uq_knowledge_bases_db_id"),)
 
     id = Column(Integer, primary_key=True, autoincrement=True)
-    db_id = Column(String(64), unique=True, nullable=False, index=True)
+    db_id = Column(String(80), unique=True, nullable=False, index=True)
     name = Column(String(255), nullable=False, index=True)
     description = Column(Text)
     kb_type = Column(String(32), nullable=False, index=True)
@@ -51,7 +51,7 @@ class KnowledgeFile(Base):
 
     id = Column(Integer, primary_key=True, autoincrement=True)
     file_id = Column(String(64), unique=True, nullable=False, index=True)
-    db_id = Column(String(64), ForeignKey("knowledge_bases.db_id", ondelete="CASCADE"), nullable=False, index=True)
+    db_id = Column(String(80), ForeignKey("knowledge_bases.db_id", ondelete="CASCADE"), nullable=False, index=True)
     parent_id = Column(String(64), ForeignKey("knowledge_files.file_id", ondelete="SET NULL"), index=True)
     filename = Column(String(512), nullable=False)
     original_filename = Column(String(512))
@@ -80,7 +80,7 @@ class EvaluationBenchmark(Base):
 
     id = Column(Integer, primary_key=True, autoincrement=True)
     benchmark_id = Column(String(64), unique=True, nullable=False, index=True)
-    db_id = Column(String(64), ForeignKey("knowledge_bases.db_id", ondelete="CASCADE"), nullable=False, index=True)
+    db_id = Column(String(80), ForeignKey("knowledge_bases.db_id", ondelete="CASCADE"), nullable=False, index=True)
     name = Column(String(255), nullable=False)
     description = Column(Text)
     question_count = Column(Integer, default=0)
@@ -100,7 +100,7 @@ class EvaluationResult(Base):
 
     id = Column(Integer, primary_key=True, autoincrement=True)
     task_id = Column(String(64), unique=True, nullable=False, index=True)
-    db_id = Column(String(64), ForeignKey("knowledge_bases.db_id", ondelete="CASCADE"), nullable=False, index=True)
+    db_id = Column(String(80), ForeignKey("knowledge_bases.db_id", ondelete="CASCADE"), nullable=False, index=True)
     benchmark_id = Column(
         String(64),
         ForeignKey("evaluation_benchmarks.benchmark_id", ondelete="SET NULL"),