diff --git a/qlib/data/dataset/processor.py b/qlib/data/dataset/processor.py
index 6de918346..194a46353 100644
--- a/qlib/data/dataset/processor.py
+++ b/qlib/data/dataset/processor.py
@@ -302,7 +302,13 @@ class CSZScoreNorm(Processor):
 
 
 class CSRankNorm(Processor):
-    """Cross Sectional Rank Normalization"""
+    """
+    Cross Sectional Rank Normalization.
+    "Cross Sectional" is often used to describe data operations.
+    The operations across different stocks are often called Cross Sectional Operation.
+    
+    For example, CSRankNorm is an operation that grouping the data by each day and rank `across` all the stocks in each day.
+    """
 
     def __init__(self, fields_group=None):
         self.fields_group = fields_group