diff --git a/docs/api/python/ndarray/ndarray.md b/docs/api/python/ndarray/ndarray.md
index dda534151a1e..fa7056933808 100644
--- a/docs/api/python/ndarray/ndarray.md
+++ b/docs/api/python/ndarray/ndarray.md
@@ -131,6 +131,7 @@ The `ndarray` package provides several classes:
     NDArray.flatten
     NDArray.expand_dims
     NDArray.split
+    NDArray.diag
 ```
 
 ### Array expand elements
diff --git a/docs/api/python/symbol/symbol.md b/docs/api/python/symbol/symbol.md
index 304b17803eda..560035429dcd 100644
--- a/docs/api/python/symbol/symbol.md
+++ b/docs/api/python/symbol/symbol.md
@@ -381,6 +381,7 @@ Composite multiple symbols into a new one by an operator.
     reshape_like
     flatten
     expand_dims
+    diag
 ```
 
 ### Expanding elements