Abstract: The transformed Eularian-mean motion equations and a quasi-geostrophic,34-level spherical coordinate model are used to discuss the physical effects of topographical and heating forcing on formation and maintenance of the summer monsoon over Asia.The computed results of the divergence of E-P flux,the forced rneridional circulation and perturbation geostrophic wind show that diabatic heating over the Qinghai-xizang plateau play an important role for formation and maintenance of the summer monsoon over Asia,and this effect is much larger than the dynamical effect of topography.The computed results also show that the effect due to the forced rreridional circulation is larger than that due to the divergence of E-P flux of forced Wayes.