diff --git a/nova/api/openstack/placement/util.py b/nova/api/openstack/placement/util.py
index 30961cd10a89..cae3f0ecb313 100644
--- a/nova/api/openstack/placement/util.py
+++ b/nova/api/openstack/placement/util.py
@@ -201,9 +201,11 @@ def trait_url(environ, trait):
 
 def validate_query_params(req, schema):
     try:
+        # NOTE(Kevin_Zheng): The webob package throws UnicodeError when
+        # param cannot be decoded. Catch this and raise HTTP 400.
         jsonschema.validate(dict(req.GET), schema,
                             format_checker=jsonschema.FormatChecker())
-    except jsonschema.ValidationError as exc:
+    except (jsonschema.ValidationError, UnicodeDecodeError) as exc:
         raise webob.exc.HTTPBadRequest(
             _('Invalid query string parameters: %(exc)s') %
             {'exc': exc})
diff --git a/nova/tests/unit/api/openstack/placement/test_util.py b/nova/tests/unit/api/openstack/placement/test_util.py
index c7b7cb4e5948..0dea037bb231 100644
--- a/nova/tests/unit/api/openstack/placement/test_util.py
+++ b/nova/tests/unit/api/openstack/placement/test_util.py
@@ -21,6 +21,7 @@ from oslo_middleware import request_id
 from oslo_utils import timeutils
 import webob
 
+import six
 import six.moves.urllib.parse as urlparse
 
 from nova.api.openstack.placement import lib as pl
@@ -146,6 +147,22 @@ class TestExtractJSON(test.NoDBTestCase):
         self.assertEqual(uuidsentinel.rp_uuid, data['uuid'])
 
 
+class QueryParamsSchemaTestCase(test.NoDBTestCase):
+
+    def test_validate_request(self):
+        schema = {
+            'type': 'object',
+            'properties': {
+                'foo': {'type': 'string'}
+             },
+            'additionalProperties': False}
+        req = webob.Request.blank('/test?foo=%88')
+        error = self.assertRaises(webob.exc.HTTPBadRequest,
+                                  util.validate_query_params,
+                                  req, schema)
+        self.assertIn('Invalid query string parameters', six.text_type(error))
+
+
 class TestJSONErrorFormatter(test.NoDBTestCase):
 
     def setUp(self):