diff --git a/nonebot/plugin/load.py b/nonebot/plugin/load.py
index 2d2c55bb..03d5dbde 100644
--- a/nonebot/plugin/load.py
+++ b/nonebot/plugin/load.py
@@ -137,6 +137,12 @@ def load_builtin_plugins(*plugins) -> Set[Plugin]:
     return load_all_plugins([f"nonebot.plugins.{p}" for p in plugins], [])
 
 
+def _find_manager_by_name(name: str) -> Optional[PluginManager]:
+    for manager in reversed(_managers):
+        if name in manager.plugins or name in manager.searched_plugins:
+            return manager
+
+
 def require(name: str) -> Export:
     """获取一个插件的导出内容。
 
@@ -148,7 +154,13 @@ def require(name: str) -> Export:
     异常:
         RuntimeError: 插件无法加载
     """
-    plugin = get_plugin(name) or load_plugin(name)
+    plugin = get_plugin(name.rsplit(".", 1)[-1])
     if not plugin:
-        raise RuntimeError(f'Cannot load plugin "{name}"!')
+        manager = _find_manager_by_name(name)
+        if manager:
+            plugin = manager.load_plugin(name)
+        else:
+            plugin = load_plugin(name)
+        if not plugin:
+            raise RuntimeError(f'Cannot load plugin "{name}"!')
     return plugin.export
diff --git a/nonebot/plugin/manager.py b/nonebot/plugin/manager.py
index c46c77c4..f359db57 100644
--- a/nonebot/plugin/manager.py
+++ b/nonebot/plugin/manager.py
@@ -53,7 +53,10 @@ class PluginManager:
 
         return [
             *chain.from_iterable(
-                [*manager.plugins, *manager.searched_plugins.keys()]
+                [
+                    *map(lambda x: x.rsplit(".", 1)[-1], manager.plugins),
+                    *manager.searched_plugins.keys(),
+                ]
                 for manager in _pre_managers
             )
         ]
@@ -65,7 +68,7 @@ class PluginManager:
         third_party_plugins: Set[str] = set()
 
         for plugin in self.plugins:
-            name = plugin.rsplit(".", 1)[-1] if "." in plugin else plugin
+            name = plugin.rsplit(".", 1)[-1]
             if name in third_party_plugins or name in previous_plugins:
                 raise RuntimeError(
                     f"Plugin already exists: {name}! Check your plugin name"
@@ -99,17 +102,23 @@ class PluginManager:
         try:
             if name in self.plugins:
                 module = importlib.import_module(name)
-            elif name not in self.searched_plugins:
-                raise RuntimeError(f"Plugin not found: {name}! Check your plugin name")
-            else:
+            elif name in self.searched_plugins:
                 module = importlib.import_module(
                     self._path_to_module_name(self.searched_plugins[name])
                 )
+            else:
+                raise RuntimeError(f"Plugin not found: {name}! Check your plugin name")
 
             logger.opt(colors=True).success(
                 f'Succeeded to import "<y>{escape_tag(name)}</y>"'
             )
-            return getattr(module, "__plugin__", None)
+            plugin = getattr(module, "__plugin__", None)
+            if plugin is None:
+                raise RuntimeError(
+                    f"Module {module.__name__} is not loaded as a plugin! "
+                    "Make sure not to import it before loading."
+                )
+            return plugin
         except Exception as e:
             logger.opt(colors=True, exception=e).error(
                 f'<r><bg #f8bbd0>Failed to import "{escape_tag(name)}"</bg #f8bbd0></r>'
diff --git a/tests/test_init.py b/tests/test_init.py
index 03da1755..1d241728 100644
--- a/tests/test_init.py
+++ b/tests/test_init.py
@@ -95,8 +95,4 @@ async def test_load_plugin(load_plugin: Set["Plugin"]):
     except RuntimeError:
         assert True
 
-    try:
-        nonebot.load_plugin("some_plugin_no_exist")
-        assert False
-    except Exception:
-        assert nonebot.get_plugin("some_plugin_no_exist") is None
+    assert nonebot.load_plugin("some_plugin_no_exist") is None