diff --git a/apps/emqx_retainer/src/emqx_retainer.erl b/apps/emqx_retainer/src/emqx_retainer.erl
index 981e6a879..cb5410cac 100644
--- a/apps/emqx_retainer/src/emqx_retainer.erl
+++ b/apps/emqx_retainer/src/emqx_retainer.erl
@@ -189,8 +189,8 @@ init([]) ->
      end}.
 
 handle_call({update_config, Conf}, _, State) ->
-    State2 = update_config(State, Conf),
-    _ = emqx:update_config([?APP], Conf),
+    {ok, Config} = emqx:update_config([?APP], Conf),
+    State2 = update_config(State, maps:get(config, Config)),
     {reply, ok, State2};
 
 handle_call({wait_semaphore, Id}, From, #{wait_quotas := Waits} = State) ->
diff --git a/apps/emqx_retainer/src/emqx_retainer_api.erl b/apps/emqx_retainer/src/emqx_retainer_api.erl
index 34e75e567..704d12deb 100644
--- a/apps/emqx_retainer/src/emqx_retainer_api.erl
+++ b/apps/emqx_retainer/src/emqx_retainer_api.erl
@@ -137,11 +137,7 @@ config(put, Req) ->
     try
         {ok, Body, _} = cowboy_req:read_body(Req),
         Cfg = emqx_json:decode(Body),
-        {ok, RawConf} = hocon:binary(jsx:encode(#{<<"mqtt_retainer">> => Cfg}),
-                                     #{format => richmap}),
-        RichConf = hocon_schema:check(emqx_retainer_schema, RawConf, #{atom_key => true}),
-        #{mqtt_retainer := Conf} = hocon_schema:richmap_to_map(RichConf),
-        emqx_retainer:update_config(Conf),
+        emqx_retainer:update_config(Cfg),
         {200,  #{<<"content-type">> => <<"text/plain">>}, <<"Update configs successfully">>}
     catch _:Reason:_ ->
             {400,
diff --git a/apps/emqx_retainer/test/emqx_retainer_SUITE.erl b/apps/emqx_retainer/test/emqx_retainer_SUITE.erl
index a2efd0357..0348e065a 100644
--- a/apps/emqx_retainer/test/emqx_retainer_SUITE.erl
+++ b/apps/emqx_retainer/test/emqx_retainer_SUITE.erl
@@ -26,59 +26,38 @@
 
 all() -> emqx_ct:all(?MODULE).
 
+-define(BASE_CONF, <<"""
+emqx_retainer {
+    enable = true
+    msg_clear_interval = 0s
+    msg_expiry_interval = 0s
+    max_payload_size = 1MB
+    flow_control {
+        max_read_number = 0
+        msg_deliver_quota = 0
+        quota_release_interval = 0s
+    }
+    config {
+        type = built_in_database
+        storage_type = ram
+        max_retained_messages = 0
+        }
+  }""">>).
+
 %%--------------------------------------------------------------------
 %% Setups
 %%--------------------------------------------------------------------
 
 init_per_suite(Config) ->
-    application:stop(emqx_retainer),
-    emqx_ct_helpers:start_apps([emqx_retainer], fun set_special_configs/1),
+    ok = emqx_config:init_load(emqx_retainer_schema, ?BASE_CONF),
+    emqx_ct_helpers:start_apps([emqx_retainer]),
     Config.
 
 end_per_suite(_Config) ->
     emqx_ct_helpers:stop_apps([emqx_retainer]).
-
-init_per_testcase(TestCase, Config) ->
-    emqx_retainer:clean(),
-    DefaultCfg = new_emqx_retainer_conf(),
-    NewCfg = case TestCase of
-                 t_message_expiry_2 ->
-                     DefaultCfg#{msg_expiry_interval := 2000};
-                 t_flow_control ->
-                     DefaultCfg#{flow_control := #{max_read_number => 1,
-                                                   msg_deliver_quota => 1,
-                                                   quota_release_interval => timer:seconds(1)}};
-                 _ ->
-                     DefaultCfg
-             end,
-    emqx_retainer:update_config(NewCfg),
-    application:ensure_all_started(emqx_retainer),
-    Config.
-
-set_special_configs(emqx_retainer) ->
-    init_emqx_retainer_conf();
-set_special_configs(_) ->
-    ok.
-
-init_emqx_retainer_conf() ->
-    emqx_config:put([?APP], new_emqx_retainer_conf()).
-
-new_emqx_retainer_conf() ->
-    #{enable => true,
-      msg_expiry_interval => 0,
-      msg_clear_interval => 0,
-      config => #{type => built_in_database,
-                  max_retained_messages => 0,
-                  storage_type => ram},
-      flow_control => #{max_read_number => 0,
-                        msg_deliver_quota => 0,
-                        quota_release_interval => 0},
-      max_payload_size => 1024 * 1024}.
-
 %%--------------------------------------------------------------------
 %% Test Cases
 %%--------------------------------------------------------------------
-
 t_store_and_clean(_) ->
     {ok, C1} = emqtt:start_link([{clean_start, true}, {proto_ver, v5}]),
     {ok, _} = emqtt:connect(C1),
@@ -184,13 +163,14 @@ t_message_expiry(_) ->
     ok = emqtt:disconnect(C1).
 
 t_message_expiry_2(_) ->
+    emqx_retainer:update_config(#{<<"msg_expiry_interval">> => <<"2s">>}),
     {ok, C1} = emqtt:start_link([{clean_start, true}, {proto_ver, v5}]),
     {ok, _} = emqtt:connect(C1),
     emqtt:publish(C1, <<"retained">>, <<"expire">>, [{qos, 0}, {retain, true}]),
 
     {ok, #{}, [0]} = emqtt:subscribe(C1, <<"retained">>, [{qos, 0}, {rh, 0}]),
     ?assertEqual(1, length(receive_messages(1))),
-    timer:sleep(3000),
+    timer:sleep(4000),
     {ok, #{}, [0]} = emqtt:subscribe(C1, <<"retained">>, [{qos, 0}, {rh, 0}]),
     ?assertEqual(0, length(receive_messages(1))),
     {ok, #{}, [0]} = emqtt:unsubscribe(C1, <<"retained">>),
@@ -216,6 +196,9 @@ t_clean(_) ->
     ok = emqtt:disconnect(C1).
 
 t_flow_control(_) ->
+    emqx_retainer:update_config(#{<<"flow_control">> => #{<<"max_read_number">> => 1,
+                                                          <<"msg_deliver_quota">> => 1,
+                                                          <<"quota_release_interval">> => <<"1s">>}}),
     {ok, C1} = emqtt:start_link([{clean_start, true}, {proto_ver, v5}]),
     {ok, _} = emqtt:connect(C1),
     emqtt:publish(C1, <<"retained/0">>, <<"this is a retained message 0">>, [{qos, 0}, {retain, true}]),
diff --git a/apps/emqx_retainer/test/mqtt_protocol_v5_SUITE.erl b/apps/emqx_retainer/test/mqtt_protocol_v5_SUITE.erl
index 70c8a0554..cba40de69 100644
--- a/apps/emqx_retainer/test/mqtt_protocol_v5_SUITE.erl
+++ b/apps/emqx_retainer/test/mqtt_protocol_v5_SUITE.erl
@@ -21,27 +21,38 @@
 
 -include_lib("eunit/include/eunit.hrl").
 
+-define(BASE_CONF, <<"""
+emqx_retainer {
+    enable = true
+    msg_clear_interval = 0s
+    msg_expiry_interval = 0s
+    max_payload_size = 1MB
+    flow_control {
+        max_read_number = 0
+        msg_deliver_quota = 0
+        quota_release_interval = 0s
+    }
+    config {
+        type = built_in_database
+        storage_type = ram
+        max_retained_messages = 0
+        }
+  }""">>).
+
 all() -> emqx_ct:all(?MODULE).
 
 init_per_suite(Config) ->
+    ok = emqx_config:init_load(emqx_retainer_schema, ?BASE_CONF),
     %% Meck emqtt
     ok = meck:new(emqtt, [non_strict, passthrough, no_history, no_link]),
     %% Start Apps
-    emqx_ct_helpers:start_apps([emqx_retainer], fun set_special_configs/1),
+    emqx_ct_helpers:start_apps([emqx_retainer]),
     Config.
 
 end_per_suite(_Config) ->
     ok = meck:unload(emqtt),
     emqx_ct_helpers:stop_apps([emqx_retainer]).
 
-%%--------------------------------------------------------------------
-%% Helpers
-%%--------------------------------------------------------------------
-set_special_configs(emqx_retainer) ->
-    emqx_retainer_SUITE:init_emqx_retainer_conf();
-set_special_configs(_) ->
-    ok.
-
 client_info(Key, Client) ->
     maps:get(Key, maps:from_list(emqtt:info(Client)), undefined).