diff --git a/python-api/requirements.txt b/python-api/requirements.txt
index 28c3c97..08afb47 100644
--- a/python-api/requirements.txt
+++ b/python-api/requirements.txt
@@ -10,7 +10,7 @@ jieba==0.38
 Jinja2==2.11.3
 lxml==4.6.3
 MarkupSafe==0.23
-nltk==3.4.5
+nltk==3.6.6
 Pillow==8.1.1
 python-dateutil==2.5.3
 pytz==2016.7
@@ -18,5 +18,5 @@ six==1.10.0
 Werkzeug==0.15.3
 Flask-SQLAlchemy==2.1
 psycopg2==2.6.2
-nltk==3.4.5
+nltk==3.6.6
 numpy==1.11.2