diff --git a/vnpy/trader/constant.py b/vnpy/trader/constant.py
index 4c83bf09..067c2a96 100644
--- a/vnpy/trader/constant.py
+++ b/vnpy/trader/constant.py
@@ -78,36 +78,34 @@ class Exchange(Enum):
     Exchange.
     """
     # Chinese
-    CFFEX = "CFFEX"
-    SHFE = "SHFE"
-    CZCE = "CZCE"
-    DCE = "DCE"
-    INE = "INE"
-    SSE = "SSE"
-    SZSE = "SZSE"
-    SGE = "SGE"
-    WXE = "WXE"     # Wuxi Steel Exchange
+    CFFEX = "CFFEX"         # China Financial Futures Exchange
+    SHFE = "SHFE"           # Shanghai Futures Exchange
+    CZCE = "CZCE"           # Zhengzhou Commodity Exchange
+    DCE = "DCE"             # Dalian Commodity Exchange
+    INE = "INE"             # Shanghai International Energy Exchange
+    SSE = "SSE"             # Shanghai Stock Exchange
+    SZSE = "SZSE"           # Shenzhen Stock Exchange
+    SGE = "SGE"             # Shanghai Gold Exchange
+    WXE = "WXE"             # Wuxi Steel Exchange
 
     # Global
-    SMART = "SMART"
-    NYMEX = "NYMEX"
-    GLOBEX = "GLOBEX"
-    IDEALPRO = "IDEALPRO"
-    CME = "CME"
-    ICE = "ICE"
-    SEHK = "SEHK"
-    HKFE = "HKFE"
-    
-    SGX = "SGX"     # Singapore Global Exchange
-    CBOT = "CBT"
-    DME = "DME"     # Dubai Mercantile Exchange
-    EUREX = "EUX"
-    APEX = "APEX"
-    LME = "LME"     # London Metal Exchange
-    BMD = "BMD"     # Bursa Malaysia Derivatives
-    TOCOM = "TOCOM" # Tokyo Commodity Exchange
-    EUNX = "EUNX"   # Euronext Exchange
-
+    SMART = "SMART"         # Smart Router for US stocks
+    NYMEX = "NYMEX"         # New York Mercantile Exchange
+    GLOBEX = "GLOBEX"       # Globex of CME
+    IDEALPRO = "IDEALPRO"   # Forex ECN of Interactive Brokers
+    CME = "CME"             # Chicago Mercantile Exchange
+    ICE = "ICE"             # Intercontinental Exchange
+    SEHK = "SEHK"           # Stock Exchange of Hong Kong
+    HKFE = "HKFE"           # Hong Kong Futures Exchange
+    SGX = "SGX"             # Singapore Global Exchange
+    CBOT = "CBT"            # Chicago Board of Trade
+    DME = "DME"             # Dubai Mercantile Exchange
+    EUREX = "EUX"           # Eurex Exchange
+    APEX = "APEX"           # Asia Pacific Exchange
+    LME = "LME"             # London Metal Exchange
+    BMD = "BMD"             # Bursa Malaysia Derivatives
+    TOCOM = "TOCOM"         # Tokyo Commodity Exchange
+    EUNX = "EUNX"           # Euronext Exchange
 
     # CryptoCurrency
     BITMEX = "BITMEX"