diff --git a/be/src/vec/functions/function_conv.cpp b/be/src/vec/functions/function_conv.cpp
index ae88f68a04..1385603ec0 100644
--- a/be/src/vec/functions/function_conv.cpp
+++ b/be/src/vec/functions/function_conv.cpp
@@ -54,9 +54,12 @@ public:
         for (int i = 0; i < 3; ++i) {
             argument_columns[i] = block.get_by_position(arguments[i]).column->convert_to_full_column_if_const();
             if (auto* nullable = check_and_get_column<ColumnNullable>(*argument_columns[i])) {
-                argument_columns[i] = nullable->get_nested_column_ptr();
+                // Danger: Here must dispose the null map data first! Because
+                // argument_columns[i]=nullable->get_nested_column_ptr(); will release the mem
+                // of column nullable mem of null map
                 VectorizedUtils::update_null_map(result_null_map_column->get_data(),
                                                  nullable->get_null_map_data());
+                argument_columns[i] = nullable->get_nested_column_ptr();
             }
         }
 
diff --git a/be/src/vec/functions/function_convert_tz.h b/be/src/vec/functions/function_convert_tz.h
index 739279d5f3..6666729208 100644
--- a/be/src/vec/functions/function_convert_tz.h
+++ b/be/src/vec/functions/function_convert_tz.h
@@ -54,9 +54,12 @@ public:
             argument_columns[i] =
                     block.get_by_position(arguments[i]).column->convert_to_full_column_if_const();
             if (auto* nullable = check_and_get_column<ColumnNullable>(*argument_columns[i])) {
-                argument_columns[i] = nullable->get_nested_column_ptr();
+                // Danger: Here must dispose the null map data first! Because
+                // argument_columns[i]=nullable->get_nested_column_ptr(); will release the mem
+                // of column nullable mem of null map
                 VectorizedUtils::update_null_map(result_null_map_column->get_data(),
                                                  nullable->get_null_map_data());
+                argument_columns[i] = nullable->get_nested_column_ptr();
             }
         }
 
diff --git a/be/src/vec/functions/function_string.h b/be/src/vec/functions/function_string.h
index 934053e107..c14e639c57 100644
--- a/be/src/vec/functions/function_string.h
+++ b/be/src/vec/functions/function_string.h
@@ -127,9 +127,12 @@ struct SubstringUtil {
             argument_columns[i] =
                     block.get_by_position(arguments[i]).column->convert_to_full_column_if_const();
             if (auto* nullable = check_and_get_column<ColumnNullable>(*argument_columns[i])) {
-                argument_columns[i] = nullable->get_nested_column_ptr();
+                // Danger: Here must dispose the null map data first! Because
+                // argument_columns[i]=nullable->get_nested_column_ptr(); will release the mem
+                // of column nullable mem of null map
                 VectorizedUtils::update_null_map(null_map->get_data(),
                                                  nullable->get_null_map_data());
+                argument_columns[i] = nullable->get_nested_column_ptr();
             }
         }
 
@@ -521,13 +524,18 @@ public:
         std::vector<const ColumnUInt8::Container*> null_list(argument_size);
 
         ColumnPtr argument_columns[argument_size];
+        ColumnPtr argument_null_columns[argument_size];
 
         for (size_t i = 0; i < argument_size; ++i) {
             argument_columns[i] =
                     block.get_by_position(arguments[i]).column->convert_to_full_column_if_const();
             if (auto* nullable = check_and_get_column<const ColumnNullable>(*argument_columns[i])) {
-                argument_columns[i] = nullable->get_nested_column_ptr();
+                // Danger: Here must dispose the null map data first! Because
+                // argument_columns[i]=nullable->get_nested_column_ptr(); will release the mem
+                // of column nullable mem of null map
                 null_list[i] = &nullable->get_null_map_data();
+                argument_null_columns[i] = nullable->get_null_map_column_ptr();
+                argument_columns[i] = nullable->get_nested_column_ptr();
             } else {
                 null_list[i] = &const_null_map->get_data();
             }
@@ -670,9 +678,12 @@ public:
             argument_columns[i] =
                     block.get_by_position(arguments[i]).column->convert_to_full_column_if_const();
             if (auto* nullable = check_and_get_column<const ColumnNullable>(*argument_columns[i])) {
-                argument_columns[i] = nullable->get_nested_column_ptr();
+                // Danger: Here must dispose the null map data first! Because
+                // argument_columns[i]=nullable->get_nested_column_ptr(); will release the mem
+                // of column nullable mem of null map
                 VectorizedUtils::update_null_map(null_map->get_data(),
                                                  nullable->get_null_map_data());
+                argument_columns[i] = nullable->get_nested_column_ptr();
             }
         }
 
@@ -817,9 +828,12 @@ public:
             argument_columns[i] =
                     block.get_by_position(arguments[i]).column->convert_to_full_column_if_const();
             if (auto* nullable = check_and_get_column<const ColumnNullable>(*argument_columns[i])) {
-                argument_columns[i] = nullable->get_nested_column_ptr();
+                // Danger: Here must dispose the null map data first! Because
+                // argument_columns[i]=nullable->get_nested_column_ptr(); will release the mem
+                // of column nullable mem of null map
                 VectorizedUtils::update_null_map(null_map->get_data(),
                                                  nullable->get_null_map_data());
+                argument_columns[i] = nullable->get_nested_column_ptr();
             }
         }
 
diff --git a/be/src/vec/functions/function_totype.h b/be/src/vec/functions/function_totype.h
index fef300e6cf..425a09b3fe 100644
--- a/be/src/vec/functions/function_totype.h
+++ b/be/src/vec/functions/function_totype.h
@@ -291,9 +291,12 @@ public:
             argument_columns[i] =
                     block.get_by_position(arguments[i]).column->convert_to_full_column_if_const();
             if (auto* nullable = check_and_get_column<ColumnNullable>(*argument_columns[i])) {
-                argument_columns[i] = nullable->get_nested_column_ptr();
+                // Danger: Here must dispose the null map data first! Because
+                // argument_columns[i]=nullable->get_nested_column_ptr(); will release the mem
+                // of column nullable mem of null map
                 VectorizedUtils::update_null_map(null_map->get_data(),
                                                  nullable->get_null_map_data());
+                argument_columns[i] = nullable->get_nested_column_ptr();
             }
         }
 
@@ -356,9 +359,12 @@ public:
             argument_columns[i] =
                     block.get_by_position(arguments[i]).column->convert_to_full_column_if_const();
             if (auto* nullable = check_and_get_column<ColumnNullable>(*argument_columns[i])) {
-                argument_columns[i] = nullable->get_nested_column_ptr();
+                // Danger: Here must dispose the null map data first! Because
+                // argument_columns[i]=nullable->get_nested_column_ptr(); will release the mem
+                // of column nullable mem of null map
                 VectorizedUtils::update_null_map(null_map->get_data(),
                                                  nullable->get_null_map_data());
+                argument_columns[i] = nullable->get_nested_column_ptr();
             }
         }