n this paper, on the basis of the daily observational data of total solar radiation of 36 years ( from 1959 to 1994 ) in Tianjin city, we set up a series of empirical formulas,by which the total solar radiaiton of different time scales ( year, season, month, dekad, pentad and day ) can be estimated through using other meteorological elements ( percentage of sunshine, and air humidity ). The mean fitting degree may reach the accuracy of 90 to 97 percent.