diff --git a/backend/alembic/README b/backend/alembic/README
new file mode 100644
index 0000000..98e4f9c
--- /dev/null
+++ b/backend/alembic/README
@@ -0,0 +1 @@
+Generic single-database configuration.
\ No newline at end of file
diff --git a/backend/alembic/env.py b/backend/alembic/env.py
new file mode 100644
index 0000000..30951e9
--- /dev/null
+++ b/backend/alembic/env.py
@@ -0,0 +1,46 @@
+from logging.config import fileConfig
+
+from alembic import context
+
+from app.config import settings
+from app.database import Base
+from app.models import *  # noqa: F401,F403
+
+config = context.config
+
+if config.config_file_name is not None:
+    fileConfig(config.config_file_name)
+
+target_metadata = Base.metadata
+
+
+def run_migrations_offline():
+    url = settings.database_url
+    context.configure(url=url, target_metadata=target_metadata, literal_binds=True)
+    with context.begin_transaction():
+        context.run_migrations()
+
+
+def do_run_migrations(connection):
+    context.configure(connection=connection, target_metadata=target_metadata)
+    with context.begin_transaction():
+        context.run_migrations()
+
+
+async def run_async_migrations():
+    from app.database import engine
+
+    async with engine.begin() as conn:
+        await conn.run_sync(do_run_migrations)
+
+
+def run_migrations_online():
+    import asyncio
+
+    asyncio.run(run_async_migrations())
+
+
+if context.is_offline_mode():
+    run_migrations_offline()
+else:
+    run_migrations_online()
diff --git a/backend/alembic/script.py.mako b/backend/alembic/script.py.mako
new file mode 100644
index 0000000..1101630
--- /dev/null
+++ b/backend/alembic/script.py.mako
@@ -0,0 +1,28 @@
+"""${message}
+
+Revision ID: ${up_revision}
+Revises: ${down_revision | comma,n}
+Create Date: ${create_date}
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+${imports if imports else ""}
+
+# revision identifiers, used by Alembic.
+revision: str = ${repr(up_revision)}
+down_revision: Union[str, Sequence[str], None] = ${repr(down_revision)}
+branch_labels: Union[str, Sequence[str], None] = ${repr(branch_labels)}
+depends_on: Union[str, Sequence[str], None] = ${repr(depends_on)}
+
+
+def upgrade() -> None:
+    """Upgrade schema."""
+    ${upgrades if upgrades else "pass"}
+
+
+def downgrade() -> None:
+    """Downgrade schema."""
+    ${downgrades if downgrades else "pass"}
diff --git a/backend/alembic/versions/ab0c56ae4242_create_users_and_audit_logs_tables.py b/backend/alembic/versions/ab0c56ae4242_create_users_and_audit_logs_tables.py
new file mode 100644
index 0000000..b973ffd
--- /dev/null
+++ b/backend/alembic/versions/ab0c56ae4242_create_users_and_audit_logs_tables.py
@@ -0,0 +1,58 @@
+"""create users and audit_logs tables
+
+Revision ID: ab0c56ae4242
+Revises:
+Create Date: 2026-07-22 16:25:22.698619
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision: str = 'ab0c56ae4242'
+down_revision: Union[str, Sequence[str], None] = None
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.create_table(
+        'users',
+        sa.Column('id', sa.String(36), primary_key=True),
+        sa.Column('username', sa.String(50), unique=True, nullable=False, index=True),
+        sa.Column('email', sa.String(255), unique=True, nullable=False),
+        sa.Column('hashed_password', sa.String(255), nullable=False),
+        sa.Column(
+            'role',
+            sa.Enum('owner', 'operator', 'viewer', name='userrole'),
+            nullable=False,
+            server_default='viewer',
+        ),
+        sa.Column('is_active', sa.Boolean, nullable=False, server_default=sa.true()),
+        sa.Column('is_approved', sa.Boolean, nullable=False, server_default=sa.false()),
+        sa.Column('login_attempts', sa.Integer, nullable=False, server_default='0'),
+        sa.Column('locked_until', sa.DateTime, nullable=True),
+        sa.Column('created_at', sa.DateTime, nullable=False, server_default=sa.func.now()),
+        sa.Column('updated_at', sa.DateTime, nullable=False, server_default=sa.func.now()),
+    )
+
+    op.create_table(
+        'audit_logs',
+        sa.Column('id', sa.String(36), primary_key=True),
+        sa.Column('user_id', sa.String(36), nullable=False, index=True),
+        sa.Column('username', sa.String(50), nullable=False),
+        sa.Column('action', sa.String(100), nullable=False, index=True),
+        sa.Column('target', sa.String(255), nullable=False),
+        sa.Column('detail', sa.Text, nullable=True),
+        sa.Column('ip_address', sa.String(45), nullable=True),
+        sa.Column('created_at', sa.DateTime, nullable=False, server_default=sa.func.now()),
+    )
+
+
+def downgrade() -> None:
+    op.drop_table('audit_logs')
+    op.drop_table('users')
+    op.execute('DROP TYPE IF EXISTS userrole')
diff --git a/backend/app/models/__init__.py b/backend/app/models/__init__.py
new file mode 100644
index 0000000..8b13789
--- /dev/null
+++ b/backend/app/models/__init__.py
@@ -0,0 +1 @@
+
diff --git a/backend/app/models/audit.py b/backend/app/models/audit.py
new file mode 100644
index 0000000..9bb03ad
--- /dev/null
+++ b/backend/app/models/audit.py
@@ -0,0 +1,20 @@
+"""审计日志 ORM 模型。"""
+import uuid
+from datetime import datetime
+from sqlalchemy import String, DateTime, Text
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.database import Base
+
+
+class AuditLog(Base):
+    __tablename__ = "audit_logs"
+
+    id: Mapped[str] = mapped_column(String(36), primary_key=True, default=lambda: str(uuid.uuid4()))
+    user_id: Mapped[str] = mapped_column(String(36), nullable=False, index=True)
+    username: Mapped[str] = mapped_column(String(50), nullable=False)
+    action: Mapped[str] = mapped_column(String(100), nullable=False, index=True)
+    target: Mapped[str] = mapped_column(String(255), nullable=False)
+    detail: Mapped[str | None] = mapped_column(Text, nullable=True)
+    ip_address: Mapped[str | None] = mapped_column(String(45), nullable=True)
+    created_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.utcnow)
diff --git a/backend/app/models/user.py b/backend/app/models/user.py
new file mode 100644
index 0000000..80af843
--- /dev/null
+++ b/backend/app/models/user.py
@@ -0,0 +1,30 @@
+"""用户 ORM 模型。"""
+import uuid
+from datetime import datetime
+from sqlalchemy import String, Boolean, DateTime, Enum as SAEnum
+from sqlalchemy.orm import Mapped, mapped_column
+import enum
+
+from app.database import Base
+
+
+class UserRole(str, enum.Enum):
+    OWNER = "owner"
+    OPERATOR = "operator"
+    VIEWER = "viewer"
+
+
+class User(Base):
+    __tablename__ = "users"
+
+    id: Mapped[str] = mapped_column(String(36), primary_key=True, default=lambda: str(uuid.uuid4()))
+    username: Mapped[str] = mapped_column(String(50), unique=True, nullable=False, index=True)
+    email: Mapped[str] = mapped_column(String(255), unique=True, nullable=False)
+    hashed_password: Mapped[str] = mapped_column(String(255), nullable=False)
+    role: Mapped[UserRole] = mapped_column(SAEnum(UserRole), default=UserRole.VIEWER, nullable=False)
+    is_active: Mapped[bool] = mapped_column(Boolean, default=True)
+    is_approved: Mapped[bool] = mapped_column(Boolean, default=False)
+    login_attempts: Mapped[int] = mapped_column(default=0)
+    locked_until: Mapped[datetime | None] = mapped_column(DateTime, nullable=True)
+    created_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.utcnow)
+    updated_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)