diff --git a/apps/emqx/src/emqx_listeners.erl b/apps/emqx/src/emqx_listeners.erl
index 410519a6c..b8205a5f6 100644
--- a/apps/emqx/src/emqx_listeners.erl
+++ b/apps/emqx/src/emqx_listeners.erl
@@ -116,6 +116,7 @@ format_raw_listeners({Type0, Conf}) ->
         fun
             ({LName, LConf0}) when is_map(LConf0) ->
                 Bind = parse_bind(LConf0),
+                MaxConn = maps:get(<<"max_connections">>, LConf0, default_max_conn()),
                 Running = is_running(Type, listener_id(Type, LName), LConf0#{bind => Bind}),
                 LConf1 = maps:remove(<<"authentication">>, LConf0),
                 LConf2 = maps:put(<<"running">>, Running, LConf1),
@@ -124,7 +125,10 @@ format_raw_listeners({Type0, Conf}) ->
                         true -> current_conns(Type, LName, Bind);
                         false -> 0
                     end,
-                LConf = maps:put(<<"current_connections">>, CurrConn, LConf2),
+                LConf = maps:merge(LConf2, #{
+                    <<"current_connections">> => CurrConn,
+                    <<"max_connections">> => ensure_max_conns(MaxConn)
+                }),
                 {true, {Type0, LName, LConf}};
             ({_LName, _MarkDel}) ->
                 false
@@ -994,3 +998,7 @@ unregister_ocsp_stapling_refresh(Type, Name) ->
 
 default_max_conn() ->
     <<"infinity">>.
+
+ensure_max_conns(<<"infinity">>) -> <<"infinity">>;
+ensure_max_conns(MaxConn) when is_binary(MaxConn) -> binary_to_integer(MaxConn);
+ensure_max_conns(MaxConn) -> MaxConn.
diff --git a/apps/emqx_management/src/emqx_mgmt_api_listeners.erl b/apps/emqx_management/src/emqx_mgmt_api_listeners.erl
index fae9228a4..36d911b7f 100644
--- a/apps/emqx_management/src/emqx_mgmt_api_listeners.erl
+++ b/apps/emqx_management/src/emqx_mgmt_api_listeners.erl
@@ -668,7 +668,13 @@ format_status(Key, Node, Listener, Acc) ->
 
 max_conn(_Int1, <<"infinity">>) -> <<"infinity">>;
 max_conn(<<"infinity">>, _Int) -> <<"infinity">>;
-max_conn(Int1, Int2) -> Int1 + Int2.
+max_conn(Int1, Int2) -> int(Int1) + int(Int2).
+
+%% If we set max_connections = “123”,
+%% it will be converted to #{<<"max_connections">> => <<"123">>} in the raw_conf with no error.
+%% so we need to convert it to integer, we should fix this at hocon lib in the future.
+int(Bin) when is_binary(Bin) -> binary_to_integer(Bin);
+int(Int) when is_integer(Int) -> Int.
 
 listener_type_status_example() ->
     [
diff --git a/apps/emqx_management/test/emqx_mgmt_api_listeners_SUITE.erl b/apps/emqx_management/test/emqx_mgmt_api_listeners_SUITE.erl
index a4ec3fe92..c47cea07e 100644
--- a/apps/emqx_management/test/emqx_mgmt_api_listeners_SUITE.erl
+++ b/apps/emqx_management/test/emqx_mgmt_api_listeners_SUITE.erl
@@ -140,6 +140,16 @@ t_list_listeners(Config) when is_list(Config) ->
     ?assertMatch(#{<<"max_connections">> := <<"infinity">>}, Create),
     ?assert(is_running(NewListenerId)),
 
+    Update2 = request(put, NewPath, [], Create#{<<"max_connections">> => 100}),
+    ?assertMatch(#{<<"max_connections">> := 100}, Update2),
+    Get2 = request(get, NewPath, [], []),
+    ?assertMatch(#{<<"max_connections">> := 100}, Get2),
+
+    Update3 = request(put, NewPath, [], Create#{<<"max_connections">> => <<"123">>}),
+    ?assertMatch(#{<<"max_connections">> := 123}, Update3),
+    Get3 = request(get, NewPath, [], []),
+    ?assertMatch(#{<<"max_connections">> := 123}, Get3),
+
     %% delete
     ?assertEqual([], delete(NewPath)),
     ?assertEqual({error, not_found}, is_running(NewListenerId)),