diff --git a/django/contrib/auth/tokens.py b/django/contrib/auth/tokens.py
index c4f2641003..15a3b0ce88 100644
--- a/django/contrib/auth/tokens.py
+++ b/django/contrib/auth/tokens.py
@@ -11,6 +11,7 @@ class PasswordResetTokenGenerator:
     reset mechanism.
     """
     key_salt = "django.contrib.auth.tokens.PasswordResetTokenGenerator"
+    algorithm = 'sha256'
     secret = settings.SECRET_KEY
 
     def make_token(self, user):
@@ -39,7 +40,14 @@ class PasswordResetTokenGenerator:
 
         # Check that the timestamp/uid has not been tampered with
         if not constant_time_compare(self._make_token_with_timestamp(user, ts), token):
-            return False
+            # RemovedInDjango40Warning: when the deprecation ends, replace
+            # with:
+            #   return False
+            if not constant_time_compare(
+                self._make_token_with_timestamp(user, ts, legacy=True),
+                token,
+            ):
+                return False
 
         # Check the timestamp is within limit.
         if (self._num_seconds(self._now()) - ts) > settings.PASSWORD_RESET_TIMEOUT:
@@ -47,7 +55,7 @@ class PasswordResetTokenGenerator:
 
         return True
 
-    def _make_token_with_timestamp(self, user, timestamp):
+    def _make_token_with_timestamp(self, user, timestamp, legacy=False):
         # timestamp is number of seconds since 2001-1-1. Converted to base 36,
         # this gives us a 6 digit string until about 2069.
         ts_b36 = int_to_base36(timestamp)
@@ -55,6 +63,10 @@ class PasswordResetTokenGenerator:
             self.key_salt,
             self._make_hash_value(user, timestamp),
             secret=self.secret,
+            # RemovedInDjango40Warning: when the deprecation ends, remove the
+            # legacy argument and replace with:
+            #   algorithm=self.algorithm,
+            algorithm='sha1' if legacy else self.algorithm,
         ).hexdigest()[::2]  # Limit to 20 characters to shorten the URL.
         return "%s-%s" % (ts_b36, hash_string)
 
diff --git a/docs/internals/deprecation.txt b/docs/internals/deprecation.txt
index db6df0fbbe..6b94bc1a3a 100644
--- a/docs/internals/deprecation.txt
+++ b/docs/internals/deprecation.txt
@@ -49,6 +49,9 @@ details on these changes.
 * Support for the pre-Django 3.1 encoding format of cookies values used by
   ``django.contrib.messages.storage.cookie.CookieStorage`` will be removed.
 
+* Support for the pre-Django 3.1 password reset tokens in the admin site (that
+  use the SHA-1 hashing algorithm) will be removed.
+
 See the :ref:`Django 3.1 release notes <deprecated-features-3.1>` for more
 details on these changes.
 
diff --git a/docs/releases/3.1.txt b/docs/releases/3.1.txt
index 6bf57e0de3..df7aad8dd2 100644
--- a/docs/releases/3.1.txt
+++ b/docs/releases/3.1.txt
@@ -56,6 +56,9 @@ Minor features
   instead of deprecated ``PASSWORD_RESET_TIMEOUT_DAYS``, which will be removed
   in Django 4.0.
 
+* The password reset mechanism now uses the SHA-256 hashing algorithm. Support
+  for tokens that use the old hashing algorithm remains until Django 4.0.
+
 :mod:`django.contrib.contenttypes`
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
diff --git a/tests/auth_tests/test_tokens.py b/tests/auth_tests/test_tokens.py
index 937fb7f598..5ac242db29 100644
--- a/tests/auth_tests/test_tokens.py
+++ b/tests/auth_tests/test_tokens.py
@@ -86,3 +86,14 @@ class TokenGeneratorTest(TestCase):
         # Tokens created with a different secret don't validate.
         self.assertIs(p0.check_token(user, tk1), False)
         self.assertIs(p1.check_token(user, tk0), False)
+
+    def test_legacy_token_validation(self):
+        # RemovedInDjango40Warning: pre-Django 3.1 tokens will be invalid.
+        user = User.objects.create_user('tokentestuser', 'test2@example.com', 'testpw')
+        p_old_generator = PasswordResetTokenGenerator()
+        p_old_generator.algorithm = 'sha1'
+        p_new_generator = PasswordResetTokenGenerator()
+
+        legacy_token = p_old_generator.make_token(user)
+        self.assertIs(p_old_generator.check_token(user, legacy_token), True)
+        self.assertIs(p_new_generator.check_token(user, legacy_token), True)