Using the stagewise moving average of the Grey System model GM (1,1) ,the trend yield Yt is simulated. According to the number of the cars and grain as well as the weight, of a grain,especially their contribution to the yield, the weight coefficients of three growing stages are developed and the climate-related yield of each stage is also found out. The predicting models for climate-related yield each stage are established with MA1CE successive regression method. And the rice yield is predicted dynamically by piecewise weighting.Finally, the yields of 1986 -1988 are estimated.