diff --git a/frontend/src/components/dialog/delete-repo-dialog.js b/frontend/src/components/dialog/delete-repo-dialog.js
index 7dc6fa39ab..a78bcd4a55 100644
--- a/frontend/src/components/dialog/delete-repo-dialog.js
+++ b/frontend/src/components/dialog/delete-repo-dialog.js
@@ -1,5 +1,6 @@
 import React, { Component } from 'react';
 import PropTypes from 'prop-types';
+import { seafileAPI } from '../../utils/seafile-api';
 import { Modal, ModalHeader, ModalBody, ModalFooter, Button } from 'reactstrap';
 import { gettext } from '../../utils/constants';
 import { Utils } from '../../utils/utils';
@@ -17,6 +18,8 @@ class DeleteRepoDialog extends Component {
     super(props);
     this.state = {
       isRequestSended: false,
+      sharedToUserCount: 0,
+      sharedToGroupCount: 0,
     };
   }
 
@@ -26,6 +29,15 @@ class DeleteRepoDialog extends Component {
     }
   }
 
+  componentDidMount() {
+    seafileAPI.getRepoShareInfo(this.props.repo.repo_id).then((res) => {
+      this.setState({
+        sharedToUserCount: res.data['shared_user_emails'].length,
+        sharedToGroupCount: res.data['shared_group_ids'].length,
+      });
+    })
+  }
+
   onDeleteRepo = () => {
     this.setState({isRequestSended: true}, () => {
       this.props.onDeleteRepo(this.props.repo);
@@ -40,6 +52,10 @@ class DeleteRepoDialog extends Component {
     let message = gettext('Are you sure you want to delete %s ?');
     message = message.replace('%s', repoName);
 
+    let alert_message = gettext('This library has been shared to {user_placeholder} users and {group_placeholder} groups.');
+    alert_message = alert_message.replace('{user_placeholder}', this.state.sharedToUserCount);
+    alert_message = alert_message.replace('{group_placeholder}', this.state.sharedToGroupCount);
+
     const { toggle: toggleDialog } = this.props;
 
     return (
@@ -47,6 +63,7 @@ class DeleteRepoDialog extends Component {
         <ModalHeader toggle={toggleDialog}>{gettext('Delete Library')}</ModalHeader>
         <ModalBody>
           <p dangerouslySetInnerHTML={{__html: message}}></p>
+          <p className="error" dangerouslySetInnerHTML={{__html: alert_message}}></p>
         </ModalBody>
         <ModalFooter>
           <Button color="secondary" onClick={toggleDialog}>{gettext('Cancel')}</Button>
diff --git a/seahub/api2/endpoints/repos.py b/seahub/api2/endpoints/repos.py
index a2c3347738..ea071ae626 100644
--- a/seahub/api2/endpoints/repos.py
+++ b/seahub/api2/endpoints/repos.py
@@ -24,7 +24,7 @@ from seahub.group.utils import group_id_to_name
 from seahub.utils import is_org_context, is_pro_version
 from seahub.utils.timeutils import timestamp_to_isoformat_timestr
 from seahub.utils.repo import get_repo_owner, is_repo_admin, \
-        repo_has_been_shared_out, get_related_users_by_repo, normalize_repo_status_code
+        repo_has_been_shared_out, normalize_repo_status_code
 
 from seahub.settings import ENABLE_STORAGE_CLASSES
 
@@ -36,7 +36,7 @@ logger = logging.getLogger(__name__)
 class ReposView(APIView):
 
     authentication_classes = (TokenAuthentication, SessionAuthentication)
-    permission_classes = (IsAuthenticated, )
+    permission_classes = (IsAuthenticated,)
     throttle_classes = (UserRateThrottle,)
 
     def get(self, request):
@@ -84,10 +84,11 @@ class ReposView(APIView):
 
             if org_id:
                 owned_repos = seafile_api.get_org_owned_repo_list(org_id,
-                        email, ret_corrupted=True)
+                                                                  email,
+                                                                  ret_corrupted=True)
             else:
                 owned_repos = seafile_api.get_owned_repo_list(email,
-                        ret_corrupted=True)
+                                                              ret_corrupted=True)
 
             # Reduce memcache fetch ops.
             modifiers_set = {x.last_modifier for x in owned_repos}
@@ -133,13 +134,11 @@ class ReposView(APIView):
 
             if org_id:
                 shared_repos = seafile_api.get_org_share_in_repo_list(org_id,
-                        email, -1, -1)
+                                                                      email, -1, -1)
             else:
-                shared_repos = seafile_api.get_share_in_repo_list(
-                        email, -1, -1)
+                shared_repos = seafile_api.get_share_in_repo_list(email, -1, -1)
 
-            repos_with_admin_share_to = ExtraSharePermission.objects.\
-                    get_repos_with_admin_permission(email)
+            repos_with_admin_share_to = ExtraSharePermission.objects.get_repos_with_admin_permission(email)
 
             # Reduce memcache fetch ops.
             owners_set = {x.user for x in shared_repos}
@@ -160,12 +159,10 @@ class ReposView(APIView):
                 if '@seafile_group' in owner_email:
                     is_group_owned_repo = True
                     group_id = get_group_id_by_repo_owner(owner_email)
-                    group_name= group_id_to_name(group_id)
+                    group_name = group_id_to_name(group_id)
 
-                owner_name = group_name if is_group_owned_repo else \
-                        nickname_dict.get(owner_email, '')
-                owner_contact_email = '' if is_group_owned_repo else \
-                        contact_email_dict.get(owner_email, '')
+                owner_name = group_name if is_group_owned_repo else nickname_dict.get(owner_email, '')
+                owner_contact_email = '' if is_group_owned_repo else contact_email_dict.get(owner_email, '')
 
                 repo_info = {
                     "type": "shared",
@@ -290,8 +287,8 @@ class ReposView(APIView):
 class RepoView(APIView):
 
     authentication_classes = (TokenAuthentication, SessionAuthentication)
-    permission_classes = (IsAuthenticated, )
-    throttle_classes = (UserRateThrottle, )
+    permission_classes = (IsAuthenticated,)
+    throttle_classes = (UserRateThrottle,)
 
     def get(self, request, repo_id):
         """ Return repo info
@@ -395,3 +392,46 @@ class RepoView(APIView):
                           repo_name=repo.name)
 
         return Response('success', status=status.HTTP_200_OK)
+
+
+class RepoShareInfoView(APIView):
+
+    authentication_classes = (TokenAuthentication, SessionAuthentication)
+    permission_classes = (IsAuthenticated,)
+    throttle_classes = (UserRateThrottle,)
+
+    def get(self, request, repo_id):
+        """ Return repo share info
+
+        Permission checking:
+        1. all authenticated user can perform this action.
+        """
+
+        # resource check
+        repo = seafile_api.get_repo(repo_id)
+        if not repo:
+            error_msg = 'Library %s not found.' % repo_id
+            return api_error(status.HTTP_404_NOT_FOUND, error_msg)
+
+        # permission check
+        permission = check_folder_permission(request, repo_id, '/')
+        if not permission:
+            error_msg = 'Permission denied.'
+            return api_error(status.HTTP_403_FORBIDDEN, error_msg)
+
+        if is_org_context(request):
+            org_id = request.user.org.org_id
+            repo_owner = seafile_api.get_org_repo_owner(org_id, repo_id)
+            shared_users = seafile_api.list_org_repo_shared_to(repo_owner, repo_id)
+            shared_groups = seafile_api.list_org_repo_shared_group(org_id, repo_owner, repo_id)
+        else:
+            repo_owner = seafile_api.get_repo_owner(repo_id)
+            shared_users = seafile_api.list_repo_shared_to(repo_owner, repo_id)
+            shared_groups = seafile_api.list_repo_shared_group_by_user(repo_owner, repo_id)
+
+        result = {
+            "shared_user_emails": [item.user for item in shared_users],
+            "shared_group_ids": [item.group_id for item in shared_groups],
+        }
+
+        return Response(result)
diff --git a/seahub/urls.py b/seahub/urls.py
index 4978ae1602..bdb42ae176 100644
--- a/seahub/urls.py
+++ b/seahub/urls.py
@@ -50,7 +50,7 @@ from seahub.api2.endpoints.repos_batch import ReposBatchView, \
         ReposAsyncBatchCopyItemView, ReposAsyncBatchMoveItemView, \
         ReposSyncBatchCopyItemView, ReposSyncBatchMoveItemView, \
         ReposBatchDeleteItemView
-from seahub.api2.endpoints.repos import RepoView, ReposView
+from seahub.api2.endpoints.repos import RepoView, ReposView, RepoShareInfoView
 from seahub.api2.endpoints.file import FileView
 from seahub.api2.endpoints.file_history import FileHistoryView, NewFileHistoryView
 from seahub.api2.endpoints.dir import DirView, DirDetailView
@@ -404,6 +404,7 @@ urlpatterns = [
     url(r'^api/v2.1/repos/(?P<repo_id>[-0-9a-f]{36})/share-links/(?P<token>[a-f0-9]+)/$', RepoShareLink.as_view(), name='api-v2.1-repo-share-link'),
     url(r'^api/v2.1/repos/(?P<repo_id>[-0-9a-f]{36})/upload-links/$', RepoUploadLinks.as_view(), name='api-v2.1-repo-upload-links'),
     url(r'^api/v2.1/repos/(?P<repo_id>[-0-9a-f]{36})/upload-links/(?P<token>[a-f0-9]+)/$', RepoUploadLink.as_view(), name='api-v2.1-repo-upload-link'),
+    url(r'^api/v2.1/repos/(?P<repo_id>[-0-9a-f]{36})/share-info/$', RepoShareInfoView.as_view(), name='api-v2.1-repo-share-info-view'),
 
     ## user:: repo-api-tokens
     url(r'^api/v2.1/repos/(?P<repo_id>[-0-9a-f]{36})/repo-api-tokens/$', RepoAPITokensView.as_view(), name='api-v2.1-repo-api-tokens'),