Abstract: In the context of a regional climate model(RegCM2),simulation is undertaken of climatic effects of changed vegetation over China with their possible mechanisms studied,reaching results which show that the changes of vegetation exert an important influence on land-air energy equilibrium. Moreover,surface-released effective thermal fluxes (sensible and latent heat) follow the change in vegetation and so does their Bowen ratio, there by resulting in the change in moist static energy distribution in the atmosphere,followed by corresponding alteration of atmospheric stratification and vertical motion,which,in turn, affects vapor transportation that,in connection with changed rising,leads to rainfall variation. In addition, the soil water content and land surface runoff may arise an evident change due to the variation of land surface evapotranspiration and soil water containing capacity.