Based on the earthquake source mechanism and seismic anisotropy, the deformation charac-teres of different tectonic layers of the lithosphere of the Qinghai-Xizang (Tibet) Plateau are discussed in this paper. In the upper crust, east-west crustal extension and strike-slip faulting are the dominant styles of deformation within the plateau, while on the margins of the plateau, thrust faulting and crustal shortening are dominant. The deformation of the middle and low crust show northeast ductile flow and clockwise rotation. Brittle deformation might occur in the uppermost mantle of southern Xizang. Finally, the authors discuss the upper mantle plastic flow and its effect on the deformation of different lithospheric layers of the plateau, and believe that the east-west crustal extension and strike-slip faulting are closely related to the northeast ductile flow of the upper mantle.