diff --git a/apps/emqx_auth/test/data/user-credentials-plain.csv b/apps/emqx_auth/test/data/user-credentials-plain.csv
new file mode 100644
index 000000000..223be0bf9
--- /dev/null
+++ b/apps/emqx_auth/test/data/user-credentials-plain.csv
@@ -0,0 +1,3 @@
+user_id,password,is_superuser
+myuser3,password3,true
+myuser4,password4,false
diff --git a/apps/emqx_auth/test/data/user-credentials-plain.json b/apps/emqx_auth/test/data/user-credentials-plain.json
new file mode 100644
index 000000000..ec5e1a82f
--- /dev/null
+++ b/apps/emqx_auth/test/data/user-credentials-plain.json
@@ -0,0 +1,12 @@
+[
+    {
+        "user_id":"myuser1",
+        "password":"password1",
+        "is_superuser": true
+    },
+    {
+        "user_id":"myuser2",
+        "password":"password2",
+        "is_superuser": false
+    }
+]
diff --git a/apps/emqx_auth_mnesia/test/emqx_authn_api_mnesia_SUITE.erl b/apps/emqx_auth_mnesia/test/emqx_authn_api_mnesia_SUITE.erl
index 2035cf2fa..71da75c1b 100644
--- a/apps/emqx_auth_mnesia/test/emqx_authn_api_mnesia_SUITE.erl
+++ b/apps/emqx_auth_mnesia/test/emqx_authn_api_mnesia_SUITE.erl
@@ -336,7 +336,13 @@ test_authenticator_import_users(PathPrefix) ->
     {ok, CSVData} = file:read_file(CSVFileName),
     {ok, 204, _} = multipart_formdata_request(ImportUri, [], [
         {filename, "user-credentials.csv", CSVData}
-    ]).
+    ]),
+
+    %% test application/json
+    {ok, 204, _} = request(post, ImportUri ++ "?type=hash", emqx_utils_json:decode(JSONData)),
+    {ok, JSONData1} = file:read_file(filename:join([Dir, <<"data/user-credentials-plain.json">>])),
+    {ok, 204, _} = request(post, ImportUri ++ "?type=plain", emqx_utils_json:decode(JSONData1)),
+    ok.
 
 %%------------------------------------------------------------------------------
 %% Helpers
diff --git a/apps/emqx_auth_mnesia/test/emqx_authn_mnesia_SUITE.erl b/apps/emqx_auth_mnesia/test/emqx_authn_mnesia_SUITE.erl
index 43b20c4fa..26ee9c406 100644
--- a/apps/emqx_auth_mnesia/test/emqx_authn_mnesia_SUITE.erl
+++ b/apps/emqx_auth_mnesia/test/emqx_authn_mnesia_SUITE.erl
@@ -253,6 +253,69 @@ t_import_users(_) ->
         )
     ).
 
+t_import_users_plain(_) ->
+    Config0 = config(),
+    Config = Config0#{password_hash_algorithm => #{name => sha256, salt_position => suffix}},
+    {ok, State} = emqx_authn_mnesia:create(?AUTHN_ID, Config),
+
+    ?assertEqual(
+        ok,
+        emqx_authn_mnesia:import_users(
+            sample_filename_and_data(plain, <<"user-credentials-plain.json">>),
+            State
+        )
+    ),
+
+    ?assertEqual(
+        ok,
+        emqx_authn_mnesia:import_users(
+            sample_filename_and_data(plain, <<"user-credentials-plain.csv">>),
+            State
+        )
+    ).
+
+t_import_users_prepared_list(_) ->
+    Config0 = config(),
+    Config = Config0#{password_hash_algorithm => #{name => sha256, salt_position => suffix}},
+    {ok, State} = emqx_authn_mnesia:create(?AUTHN_ID, Config),
+
+    Users1 = [
+        #{<<"user_id">> => <<"u1">>, <<"password">> => <<"p1">>, <<"is_superuser">> => true},
+        #{<<"user_id">> => <<"u2">>, <<"password">> => <<"p2">>, <<"is_superuser">> => true}
+    ],
+    Users2 = [
+        #{
+            <<"user_id">> => <<"u3">>,
+            <<"password_hash">> =>
+                <<"c5e46903df45e5dc096dc74657610dbee8deaacae656df88a1788f1847390242">>,
+            <<"salt">> => <<"e378187547bf2d6f0545a3f441aa4d8a">>,
+            <<"is_superuser">> => true
+        },
+        #{
+            <<"user_id">> => <<"u4">>,
+            <<"password_hash">> =>
+                <<"f4d17f300b11e522fd33f497c11b126ef1ea5149c74d2220f9a16dc876d4567b">>,
+            <<"salt">> => <<"6d3f9bd5b54d94b98adbcfe10b6d181f">>,
+            <<"is_superuser">> => true
+        }
+    ],
+
+    ?assertEqual(
+        ok,
+        emqx_authn_mnesia:import_users(
+            {plain, prepared_user_list, Users1},
+            State
+        )
+    ),
+
+    ?assertEqual(
+        ok,
+        emqx_authn_mnesia:import_users(
+            {hash, prepared_user_list, Users2},
+            State
+        )
+    ).
+
 %%------------------------------------------------------------------------------
 %% Helpers
 %%------------------------------------------------------------------------------
@@ -262,9 +325,12 @@ sample_filename(Name) ->
     filename:join([Dir, <<"data">>, Name]).
 
 sample_filename_and_data(Name) ->
+    sample_filename_and_data(hash, Name).
+
+sample_filename_and_data(Type, Name) ->
     Filename = sample_filename(Name),
     {ok, Data} = file:read_file(Filename),
-    {hash, Filename, Data}.
+    {Type, Filename, Data}.
 
 config() ->
     #{