diff -Nura gnome-shell-3.38.3/js/ui/status/keyboard.js gnome-shell-3.38.3_new/js/ui/status/keyboard.js
--- gnome-shell-3.38.3/js/ui/status/keyboard.js	2021-01-15 01:51:55.673968800 +0800
+++ gnome-shell-3.38.3_new/js/ui/status/keyboard.js	2021-03-17 19:01:52.594128367 +0800
@@ -264,6 +264,33 @@
         this._settings.connect('changed::%s'.format(this._KEY_INPUT_SOURCES), this._emitInputSourcesChanged.bind(this));
         this._settings.connect('changed::%s'.format(this._KEY_KEYBOARD_OPTIONS), this._emitKeyboardOptionsChanged.bind(this));
         this._settings.connect('changed::%s'.format(this._KEY_PER_WINDOW), this._emitPerWindowChanged.bind(this));
+
+        let sources = this._settings.get_value(this._KEY_INPUT_SOURCES);
+        let nSources = sources.n_children();
+        let sourcesList = [];
+
+        if (nSources <= 1) {
+            if (GLib.getenv('LANG') == 'zh_CN.UTF-8') {
+                log('Set default input method in Chinese language env.');
+                sourcesList.push(['xkb', 'cn']);
+                sourcesList.push([ "ibus", "libpinyin" ]);
+            }
+
+            else if (GLib.getenv('LANG') == 'ja_JP.UTF-8') {
+                log('Set default input method in Japanese language env.');
+                sourcesList.push([ "ibus", "mozc-jp" ]);
+                sourcesList.push(['xkb', 'jp']);
+            }
+
+            else if (GLib.getenv('LANG') == 'ko_KR.UTF-8') {
+                log('Set default input method in Korean language env.');
+                sourcesList.push(['xkb', 'kr']);
+                sourcesList.push([ "ibus", "hangul" ]);
+            }
+
+            let params = GLib.Variant.new('a(ss)', sourcesList);
+            this._settings.set_value(this._KEY_INPUT_SOURCES, params);
+        }
     }
 
     _getSourcesList(key) {