diff --git a/tornado/platform/asyncio.py b/tornado/platform/asyncio.py
index 58d31ddd81..838055a7f5 100644
--- a/tornado/platform/asyncio.py
+++ b/tornado/platform/asyncio.py
@@ -74,20 +74,6 @@ def _atexit_callback() -> None:
 
 atexit.register(_atexit_callback)
 
-if sys.version_info >= (3, 10):
-
-    def _get_event_loop() -> asyncio.AbstractEventLoop:
-        try:
-            return asyncio.get_running_loop()
-        except RuntimeError:
-            pass
-
-        return asyncio.get_event_loop_policy().get_event_loop()
-
-
-else:
-    from asyncio import get_event_loop as _get_event_loop
-
 
 class BaseAsyncIOLoop(IOLoop):
     def initialize(  # type: ignore
@@ -207,15 +193,7 @@ def _handle_events(self, fd: int, events: int) -> None:
         handler_func(fileobj, events)
 
     def start(self) -> None:
-        try:
-            old_loop = _get_event_loop()
-        except (RuntimeError, AssertionError):
-            old_loop = None  # type: ignore
-        try:
-            asyncio.set_event_loop(self.asyncio_loop)
-            self.asyncio_loop.run_forever()
-        finally:
-            asyncio.set_event_loop(old_loop)
+        self.asyncio_loop.run_forever()
 
     def stop(self) -> None:
         self.asyncio_loop.stop()