Both the significant increase in aerosol concentration of East Asia in recent years and the global Sea Surface Temperature (SST) decadal change around 1976 have significant effects on East Asian precipitation. So we use CAM3.0 model to investigate the respective effect of these two phenomena on East Asia in boreal summer. By separately doubling the concentration of the sulfate aerosol and that of black carbon aerosol and doubling both of them in East Asia (100?150 0E,20?50 0N),the climate effects of these aerosol species are investigated. And the influence of global change of SST around 1976/1977 on the East Asia Summer Monsoon is also considered in the same model. The results show that all the four experiments could lead to rainfall decreasing in the center of East Asia, north of the Yangtze River but increasing in regions along the Southeastern China coast, similar to a pattern of "southern flood and northern drought". However, the differences of rainfall in Northwest Pacific and North Indian Ocean and the different patterns of wind field changing between the aerosol experiment and SST experiment indicate the presence of different mechanisms. Three experiments on aerosol show that the scattering effect is the main climate effect of sulphate and black carbon aerosols on the Easter Asian summer. The sulphate aerosol experiment has the most significant temperature decreasing and sinking anomaly, while the black carbon aerosol leads to weakened sinking anomaly. This weakened sinking is south to that induced by sulphate aerosol, and its compensating rising flow results in more rainfall in the south. When both of the aerosols concentration increased synchronously, the anomalous rainfall distribution is somewhat like that in black carbon aerosol experiment but with less intensity.