diff --git a/src/memos/vec_dbs/milvus.py b/src/memos/vec_dbs/milvus.py
index 3963e6e4a..e63cabf6f 100644
--- a/src/memos/vec_dbs/milvus.py
+++ b/src/memos/vec_dbs/milvus.py
@@ -363,6 +363,16 @@ def _handle_field_conditions(self, condition_dict: dict[str, Any]) -> str:
 
     def _build_field_expression(self, field: str, value: Any) -> str:
         """Build expression for a single field."""
+        # Convert date-time format from 'YYYY-MM-DD HH:MM:SS' to 'YYYY-MM-DDTHH:MM:SS' for comparison
+        if (field == "created_at" or field == "updated_at") and isinstance(value, str):
+            # Replace space with 'T' to match ISO 8601 format
+            value = value.replace(" ", "T")
+        elif (field == "created_at" or field == "updated_at") and isinstance(value, dict):
+            # Handle dict case (e.g., {"gte": "2026-02-09 15:43:12"})
+            for op, operand in value.items():
+                if isinstance(operand, str):
+                    value[op] = operand.replace(" ", "T")
+
         # Handle comparison operators
         if isinstance(value, dict):
             if len(value) == 1:
@@ -435,6 +445,11 @@ def _handle_comparison_operator(self, field: str, operator: str, value: Any) ->
         """Handle comparison operators (gte, lte, gt, lt, ne)."""
         milvus_op = {"gte": ">=", "lte": "<=", "gt": ">", "lt": "<", "ne": "!="}.get(operator, "==")
 
+        # Convert date-time format from 'YYYY-MM-DD HH:MM:SS' to 'YYYY-MM-DDTHH:MM:SS' for comparison
+        if (field == "created_at" or field == "updated_at") and isinstance(value, str):
+            # Replace space with 'T' to match ISO 8601 format
+            value = value.replace(" ", "T")
+
         formatted_value = self._format_value(value)
         return f"payload['{field}'] {milvus_op} {formatted_value}"
 
@@ -520,7 +535,9 @@ def get_by_filter(
         Returns:
             List of items including vectors and payload that match the filter
         """
+        logger.info(f"filter for milvus: {filter}")
         expr = self._dict_to_expr(filter) if filter else ""
+        logger.info(f"filter expr for milvus: {expr}")
         all_items = []
 
         # Use query_iterator for efficient pagination