diff --git a/src/promptflow/CHANGELOG.md b/src/promptflow/CHANGELOG.md
index 6292c450be4..df09ad4473b 100644
--- a/src/promptflow/CHANGELOG.md
+++ b/src/promptflow/CHANGELOG.md
@@ -2,9 +2,16 @@
 
 ## 1.4.0 (Upcoming)
 
+### Features Added
+
+- [Executor] Calculate system_metrics recursively in api_calls.
+- [Executor] Add flow root level api_calls, so that user can overview the aggregated metrics of a flow.
+- [Executor] Add @trace decorator to make it possible to log traces for functions that are called by tools.
+
 ### Bugs Fixed
 
 - Fix unaligned inputs & outputs or pandas exception during get details against run in Azure.
+- Fix loose flow path validation for run schema.
 
 ## 1.3.0 (2023.12.27)
 
@@ -13,9 +20,6 @@
 - Add support to configure prompt flow home directory via environment variable `PF_HOME_DIRECTORY`.
   - Please set before importing `promptflow`, otherwise it won't take effect.
 - [Executor] Handle KeyboardInterrupt in flow test so that the final state is Canceled.
-- [Executor] Calculate system_metrics recursively in api_calls.
-- [Executor] Add flow root level api_calls, so that user can overview the aggregated metrics of a flow.
-- [Executor] Add @trace decorator to make it possible to log traces for functions that are called by tools.
 
 ### Bugs Fixed
 - [SDK/CLI] Fix single node run doesn't work when consuming sub item of upstream node
diff --git a/src/promptflow/promptflow/_sdk/schemas/_run.py b/src/promptflow/promptflow/_sdk/schemas/_run.py
index d4963583349..6287c273791 100644
--- a/src/promptflow/promptflow/_sdk/schemas/_run.py
+++ b/src/promptflow/promptflow/_sdk/schemas/_run.py
@@ -48,6 +48,23 @@ def _validate(self, value):
             )
 
 
+class RemoteFlowStr(fields.Str):
+    default_error_messages = {
+        "invalid_path": "Invalid remote flow path. Currently only azureml:<flow-name> is supported",
+    }
+
+    def _validate(self, value):
+        # inherited validations like required, allow_none, etc.
+        super(RemoteFlowStr, self)._validate(value)
+
+        if value is None:
+            return
+        if not isinstance(value, str) or not value.startswith("azureml:"):
+            raise self.make_error(
+                "invalid_path",
+            )
+
+
 class RunSchema(YamlFileSchema):
     """Base schema for all run schemas."""
 
@@ -60,7 +77,7 @@ class RunSchema(YamlFileSchema):
     properties = fields.Dict(keys=fields.Str(), values=fields.Str(allow_none=True))
     # endregion: common fields
 
-    flow = UnionField([LocalPathField(required=True), fields.Str(required=True)])
+    flow = UnionField([LocalPathField(required=True), RemoteFlowStr(required=True)])
     # inputs field
     data = UnionField([LocalPathField(), RemotePathStr()])
     column_mapping = fields.Dict(keys=fields.Str)
diff --git a/src/promptflow/tests/sdk_cli_test/unittests/test_run.py b/src/promptflow/tests/sdk_cli_test/unittests/test_run.py
index 6de1203a24a..d4f7da8a93b 100644
--- a/src/promptflow/tests/sdk_cli_test/unittests/test_run.py
+++ b/src/promptflow/tests/sdk_cli_test/unittests/test_run.py
@@ -94,6 +94,20 @@ def test_dot_env_resolve(self):
         run = load_run(source=source, params_override=[{"name": run_id}])
         assert run.environment_variables == {"FOO": "BAR"}
 
+    def test_run_invalid_flow_path(self):
+        run_id = str(uuid.uuid4())
+        source = f"{RUNS_DIR}/bulk_run_invalid_flow_path.yaml"
+        with pytest.raises(ValidationError) as e:
+            load_run(source=source, params_override=[{"name": run_id}])
+        assert "Can't find directory or file in resolved absolute path:" in str(e.value)
+
+    def test_run_invalid_remote_flow(self):
+        run_id = str(uuid.uuid4())
+        source = f"{RUNS_DIR}/bulk_run_invalid_remote_flow_str.yaml"
+        with pytest.raises(ValidationError) as e:
+            load_run(source=source, params_override=[{"name": run_id}])
+        assert "Invalid remote flow path. Currently only azureml:<flow-name> is supported" in str(e.value)
+
     def test_data_not_exist_validation_error(self):
         source = f"{RUNS_DIR}/sample_bulk_run.yaml"
         with pytest.raises(ValidationError) as e:
diff --git a/src/promptflow/tests/test_configs/runs/bulk_run_invalid_flow_path.yaml b/src/promptflow/tests/test_configs/runs/bulk_run_invalid_flow_path.yaml
new file mode 100644
index 00000000000..d6d4d3756d1
--- /dev/null
+++ b/src/promptflow/tests/test_configs/runs/bulk_run_invalid_flow_path.yaml
@@ -0,0 +1,11 @@
+name: flow_run_20230629_101205
+description: sample bulk run
+# flow relative to current working directory should not be supported.
+flow: tests/test_configs/flows/web_classification
+data: ../datas/webClassification1.jsonl
+column_mapping:
+   url: "${data.url}"
+variant: ${summarize_text_content.variant_0}
+
+# run config: env related
+environment_variables: env_file
diff --git a/src/promptflow/tests/test_configs/runs/bulk_run_invalid_remote_flow_str.yaml b/src/promptflow/tests/test_configs/runs/bulk_run_invalid_remote_flow_str.yaml
new file mode 100644
index 00000000000..ed607e14e99
--- /dev/null
+++ b/src/promptflow/tests/test_configs/runs/bulk_run_invalid_remote_flow_str.yaml
@@ -0,0 +1,11 @@
+name: flow_run_20230629_101205
+description: sample bulk run
+# invalid remote flow format should not be supported.
+flow: invalid_remote_flow
+data: ../datas/webClassification1.jsonl
+column_mapping:
+   url: "${data.url}"
+variant: ${summarize_text_content.variant_0}
+
+# run config: env related
+environment_variables: env_file