diff --git a/funcat/func.py b/funcat/func.py
index aca5846..9fbf32a 100644
--- a/funcat/func.py
+++ b/funcat/func.py
@@ -75,11 +75,12 @@ class SMASeries(TwoArgumentSeries):
     """同花顺专用SMA"""
 
     def func(self, series, n, _):
-        results = np.nan_to_num(series).copy()
+        # results = np.nan_to_num(series).copy()
         # FIXME this is very slow
-        for i in range(1, len(series)):
-            results[i] = ((n - 1) * results[i - 1] + results[i]) / n
-        return results
+        # for i in range(1, len(series)):
+        #     results[i] = ((n - 1) * results[i - 1] + results[i]) / n
+        results = series.fillna(0)
+        return results.ewm(min_periods=0, ignore_na=False, adjust=False, alpha=1/n).mean()
 
 
 class SumSeries(NumericSeries):