Abstract: In this article the 500mb height of each pentad in the period 1954-1975 in the area 15-65°N, 75-155°E are resolved with Chebyshev Polynomials. Some main coefficients are obtained, the physical explanation of these coefficients as well as the relationships of these coefficients with temperature and rainfall in our country are discussed. The main results are as following: 1.The coefficients A10, A01 which express the meridional and zonal circulation of atmosphere are correlated with the 10-year running means of temperature grade and monthly average temperature of all parts of our country. This correlation make it possible to forecast the tendency of temperature. 2.A multicorrelation table, formed by the December coefficient A00 which expresses average height and January coefficient A10 in same winter is a possible tool for forecasting the tendency of rainfall in coming the rainy season (May-August) of the middle and Lower Reaches of Yangtze. Good results have been obtamed in three-year applications.