diff --git a/deploy/aliyun_host.py b/deploy/aliyun_host.py
index 7bba478..b5d7e5a 100644
--- a/deploy/aliyun_host.py
+++ b/deploy/aliyun_host.py
@@ -216,15 +216,18 @@ def create_params(cfg):
         raise CloudError(
             "creation requires approved image/type/VSwitch/security group/SSH KeyPair"
         )
+    spot_strategy = cfg.get("spot_strategy", "SpotWithPriceLimit")
+    if spot_strategy not in ("SpotWithPriceLimit", "SpotAsPriceGo"):
+        raise CloudError("spot_strategy must be SpotWithPriceLimit or SpotAsPriceGo")
     price = cfg.get("spot_price_limit")
-    if (
+    if spot_strategy == "SpotWithPriceLimit" and (
         isinstance(price, bool)
         or not isinstance(price, (int, float))
         or not math.isfinite(price)
         or price <= 0
     ):
         raise CloudError(
-            "a positive, finite spot_price_limit approved by the owner is required"
+            "a positive, finite spot_price_limit is required for SpotWithPriceLimit"
         )
     disk = cfg.get("system_disk_gib", 40)
     if isinstance(disk, bool) or not isinstance(disk, int) or not 40 <= disk <= 200:
@@ -241,14 +244,15 @@ def create_params(cfg):
         "InstanceName": cfg["project_tag"],
         "InstanceChargeType": "PostPaid",
         "InternetMaxBandwidthOut": 0,
-        "SpotStrategy": "SpotWithPriceLimit",
-        "SpotPriceLimit": price,
+        "SpotStrategy": spot_strategy,
         "SystemDisk.Category": cfg.get("system_disk_category", "cloud_essd"),
         "SystemDisk.Size": disk,
         "SystemDisk.PerformanceLevel": cfg.get("system_disk_performance_level", "PL1"),
         "Tag.1.Key": "project",
         "Tag.1.Value": cfg["project_tag"],
     }
+    if spot_strategy == "SpotWithPriceLimit":
+        params["SpotPriceLimit"] = price
     user_data_file = cfg.get("user_data_file")
     if user_data_file is not None:
         if not isinstance(user_data_file, str) or not user_data_file.strip():
diff --git a/tests/test_deployment.py b/tests/test_deployment.py
index 90dae3d..c97a3ba 100644
--- a/tests/test_deployment.py
+++ b/tests/test_deployment.py
@@ -138,6 +138,14 @@ class CloudTests(unittest.TestCase):
         self.assertEqual(params["SystemDisk.PerformanceLevel"], "PL1")
         self.assertEqual(api.mutations(), ["RunInstances", "AssociateEipAddress"])
 
+    def test_automatic_spot_price_omits_price_limit(self):
+        cfg = config()
+        cfg["spot_strategy"] = "SpotAsPriceGo"
+        cfg.pop("spot_price_limit")
+        params = cloud.create_params(cfg)
+        self.assertEqual(params["SpotStrategy"], "SpotAsPriceGo")
+        self.assertNotIn("SpotPriceLimit", params)
+
     def test_user_data_is_base64_encoded_without_logging_content(self):
         with tempfile.TemporaryDirectory() as d:
             user_data = Path(d) / "bootstrap.sh"