diff --git a/README.md b/README.md
index 0e9440b2f..3fd71fae5 100644
--- a/README.md
+++ b/README.md
@@ -125,6 +125,19 @@ Commands:
 ```
 To list the options for each command, execute `vectordbbench [command] --help`
 
+`milvusautoindex` and `zillizautoindex` accept `--level` from 1 to 10 (YAML:
+`level`) on servers that support AutoIndex search levels. If omitted, Milvus
+sends no level, preserving the server's default behavior; Zilliz Cloud keeps
+its existing default of 1 and always sends it. Results record the value in
+`task_config.db_case_config.level`.
+
+```shell
+vectordbbench milvusautoindex \
+  --uri http://localhost:19530 \
+  --level 2 \
+  <other options>
+```
+
 Use `--note` or `--note-file` to preserve deployment, resource, client, network, and constraint context in each result JSON under `task_config.db_config.note`. The options are mutually exclusive. Prefer `--note-file` for structured or multiline context, and never include credentials, tokens, or sensitive connection details.
 
 ```shell
diff --git a/tests/test_milvus_zilliz_cli.py b/tests/test_milvus_zilliz_cli.py
index 4177c8898..967e5f109 100644
--- a/tests/test_milvus_zilliz_cli.py
+++ b/tests/test_milvus_zilliz_cli.py
@@ -1,3 +1,4 @@
+import pytest
 from click.testing import CliRunner
 from pytest import MonkeyPatch
 
@@ -55,6 +56,56 @@ def fake_run(**kwargs):
     assert captured["db_case_config"].use_partition_key is True
 
 
+@pytest.mark.parametrize(
+    ("level_args", "expected_level"),
+    [(["--level", "2"], 2), ([], None)],
+)
+def test_milvus_autoindex_cli_handles_search_level(
+    monkeypatch: MonkeyPatch,
+    level_args: list[str],
+    expected_level: int | None,
+) -> None:
+    captured = {}
+
+    def fake_run(**kwargs):
+        captured.update(kwargs)
+
+    monkeypatch.setattr(milvus_cli, "run", fake_run)
+
+    result = CliRunner().invoke(
+        milvus_cli.MilvusAutoIndex,
+        ["--uri", "http://localhost:19530", *level_args, "--dry-run"],
+    )
+
+    assert result.exit_code == 0, result.output
+    config = captured["db_case_config"]
+    assert config.level == expected_level
+    if expected_level is None:
+        assert "params" not in config.search_param()
+
+
+def test_milvus_flat_cli_rejects_search_level() -> None:
+    result = CliRunner().invoke(
+        milvus_cli.MilvusFlat,
+        ["--uri", "http://localhost:19530", "--level", "2", "--dry-run"],
+    )
+
+    assert result.exit_code == 2
+    assert "No such option" in result.output
+    assert "--level" in result.output
+
+
+@pytest.mark.parametrize("level", ["0", "11"])
+def test_milvus_autoindex_cli_rejects_out_of_range_level(level: str) -> None:
+    result = CliRunner().invoke(
+        milvus_cli.MilvusAutoIndex,
+        ["--uri", "http://localhost:19530", "--level", level, "--dry-run"],
+    )
+
+    assert result.exit_code == 2
+    assert "1<=x<=10" in result.output
+
+
 def test_zilliz_autoindex_cli_enables_partition_key_for_multitenant_case(
     monkeypatch: MonkeyPatch,
 ) -> None:
diff --git a/vectordb_bench/backend/clients/milvus/cli.py b/vectordb_bench/backend/clients/milvus/cli.py
index 738248ac3..ec11015c8 100644
--- a/vectordb_bench/backend/clients/milvus/cli.py
+++ b/vectordb_bench/backend/clients/milvus/cli.py
@@ -5,6 +5,7 @@
 
 from vectordb_bench.backend.clients import DB
 from vectordb_bench.cli.cli import (
+    AutoIndexLevelTypedDict,
     CommonTypedDict,
     HNSWFlavor3,
     IVFFlatTypedDictN,
@@ -100,7 +101,7 @@ class MilvusTypedDict(TypedDict):
     ]
 
 
-class MilvusAutoIndexTypedDict(CommonTypedDict, MilvusTypedDict): ...
+class MilvusAutoIndexTypedDict(CommonTypedDict, MilvusTypedDict, AutoIndexLevelTypedDict): ...
 
 
 @cli.command()
@@ -111,14 +112,17 @@ def MilvusAutoIndex(**parameters: Unpack[MilvusAutoIndexTypedDict]):
     run(
         db=DBTYPE,
         db_config=_build_milvus_config(parameters),
-        db_case_config=_with_partition_key(AutoIndexConfig(), parameters),
+        db_case_config=_with_partition_key(AutoIndexConfig(level=parameters["level"]), parameters),
         **parameters,
     )
 
 
+class MilvusFlatTypedDict(CommonTypedDict, MilvusTypedDict): ...
+
+
 @cli.command()
-@click_parameter_decorators_from_typed_dict(MilvusAutoIndexTypedDict)
-def MilvusFlat(**parameters: Unpack[MilvusAutoIndexTypedDict]):
+@click_parameter_decorators_from_typed_dict(MilvusFlatTypedDict)
+def MilvusFlat(**parameters: Unpack[MilvusFlatTypedDict]):
     from .config import FLATConfig
 
     run(
diff --git a/vectordb_bench/backend/clients/milvus/config.py b/vectordb_bench/backend/clients/milvus/config.py
index 99d5ac8cf..caa9a82e2 100644
--- a/vectordb_bench/backend/clients/milvus/config.py
+++ b/vectordb_bench/backend/clients/milvus/config.py
@@ -1,6 +1,6 @@
-from typing import ClassVar
+from typing import Annotated, ClassVar
 
-from pydantic import BaseModel, SecretStr
+from pydantic import BaseModel, Field, SecretStr
 
 from ..api import DBCaseConfig, DBConfig, IndexType, MetricType, SQType
 
@@ -51,8 +51,12 @@ def parse_metric(self) -> str:
         return self.metric_type.value
 
 
+AutoIndexLevel = Annotated[int, Field(ge=1, le=10)]
+
+
 class AutoIndexConfig(MilvusIndexConfig, DBCaseConfig):
     index: IndexType = IndexType.AUTOINDEX
+    level: AutoIndexLevel | None = None
 
     def index_param(self) -> dict:
         return {
@@ -62,9 +66,10 @@ def index_param(self) -> dict:
         }
 
     def search_param(self) -> dict:
-        return {
-            "metric_type": self.parse_metric(),
-        }
+        params = {"metric_type": self.parse_metric()}
+        if self.level is not None:
+            params["params"] = {"level": self.level}
+        return params
 
 
 class HNSWConfig(MilvusIndexConfig, DBCaseConfig):
diff --git a/vectordb_bench/backend/clients/zilliz_cloud/cli.py b/vectordb_bench/backend/clients/zilliz_cloud/cli.py
index 030a00661..0a127b249 100644
--- a/vectordb_bench/backend/clients/zilliz_cloud/cli.py
+++ b/vectordb_bench/backend/clients/zilliz_cloud/cli.py
@@ -6,6 +6,7 @@
 
 from vectordb_bench.backend.clients import DB
 from vectordb_bench.cli.cli import (
+    AutoIndexLevelTypedDict,
     CommonTypedDict,
     cli,
     click_parameter_decorators_from_typed_dict,
@@ -49,10 +50,6 @@ class ZillizTypedDict(CommonTypedDict):
             show_default="$ZILLIZ_TOKEN",
         ),
     ]
-    level: Annotated[
-        str,
-        click.option("--level", type=str, help="Zilliz index level", required=False),
-    ]
     num_shards: Annotated[
         int,
         click.option(
@@ -88,9 +85,12 @@ class ZillizTypedDict(CommonTypedDict):
     ]
 
 
+class ZillizAutoIndexTypedDict(ZillizTypedDict, AutoIndexLevelTypedDict): ...
+
+
 @cli.command()
-@click_parameter_decorators_from_typed_dict(ZillizTypedDict)
-def ZillizAutoIndex(**parameters: Unpack[ZillizTypedDict]):
+@click_parameter_decorators_from_typed_dict(ZillizAutoIndexTypedDict)
+def ZillizAutoIndex(**parameters: Unpack[ZillizAutoIndexTypedDict]):
     from .config import AutoIndexConfig, ZillizCloudConfig
 
     run(
@@ -105,7 +105,7 @@ def ZillizAutoIndex(**parameters: Unpack[ZillizTypedDict]):
             collection_name=parameters["collection_name"],
         ),
         db_case_config=AutoIndexConfig(
-            level=int(parameters["level"]) if parameters["level"] else 1,
+            level=parameters["level"] if parameters["level"] is not None else 1,
             num_shards=parameters["num_shards"],
             use_partition_key=_use_partition_key(parameters),
         ),
diff --git a/vectordb_bench/backend/clients/zilliz_cloud/config.py b/vectordb_bench/backend/clients/zilliz_cloud/config.py
index ee5ecf645..9db9f2b8f 100644
--- a/vectordb_bench/backend/clients/zilliz_cloud/config.py
+++ b/vectordb_bench/backend/clients/zilliz_cloud/config.py
@@ -1,7 +1,12 @@
 from pydantic import SecretStr
 
-from ..api import DBCaseConfig, DBConfig
-from ..milvus.config import IndexType, MilvusFtsConfig, MilvusIndexConfig
+from ..api import DBConfig
+from ..milvus.config import AutoIndexConfig as MilvusAutoIndexConfig
+from ..milvus.config import (
+    AutoIndexLevel,
+    IndexType,
+    MilvusFtsConfig,
+)
 
 
 class ZillizCloudConfig(DBConfig):
@@ -27,9 +32,8 @@ def to_dict(self) -> dict:
         }
 
 
-class AutoIndexConfig(MilvusIndexConfig, DBCaseConfig):
-    index: IndexType = IndexType.AUTOINDEX
-    level: int = 1
+class AutoIndexConfig(MilvusAutoIndexConfig):
+    level: AutoIndexLevel = 1
     num_shards: int = 1
 
     def index_param(self) -> dict:
@@ -39,14 +43,6 @@ def index_param(self) -> dict:
             "params": {"shardsNum": self.num_shards},
         }
 
-    def search_param(self) -> dict:
-        return {
-            "metric_type": self.parse_metric(),
-            "params": {
-                "level": self.level,
-            },
-        }
-
 
 class ZillizCloudFtsConfig(MilvusFtsConfig):
     index_type: str = IndexType.AUTOINDEX.value
diff --git a/vectordb_bench/cli/cli.py b/vectordb_bench/cli/cli.py
index c0f3798c9..9f4b5735d 100644
--- a/vectordb_bench/cli/cli.py
+++ b/vectordb_bench/cli/cli.py
@@ -825,6 +825,18 @@ class HNSWBaseTypedDict(TypedDict):
     ]
 
 
+class AutoIndexLevelTypedDict(TypedDict):
+    level: Annotated[
+        int | None,
+        click.option(
+            "--level",
+            type=click.IntRange(1, 10),
+            default=None,
+            help="AutoIndex search level (1-10).",
+        ),
+    ]
+
+
 class HNSWBaseRequiredTypedDict(TypedDict):
     m: Annotated[int | None, click.option("--m", type=int, help="hnsw m", required=True)]
     ef_construction: Annotated[