The effect of north Pacific SST anomaly in the middle latitute,which is both active and significantly correlative with rainfall in China,on precipitation was simulated by means of OSU-AGCM.The results show that SST decrease in a large scale may cause more rainfall in north China and less precipitation in south China with a boundary at about 40°N latatute.At the same time significant changes take place for precipitation in north Pacific in the middle and low latitute.The mechanism of the impact of SST anomaly on precipitation was discussed through analysing the variation of the atmospheric physical fields caused by SST anomaly and some useful results were obtained.