Abstract: The key to adjust indicators of our country seasonally lies in the transformation from Gregorian calendar to traditional Chinese calendar. There is nothing else different from other developed countries. As to the data seasonally adjusted with traditional Chinese calendar, X-12 can be used for the following process. There are several methods to reduce the influence of traditional Chinese calendar. This paper proposes to apportion the tendency in data and to fix the seasonal factors in order to reduce the influence of traditional Chinese calendar.