Abstract: The tectonic deformation in Qinghai-Tibet plateau displays strong compression, shortening and thrust in South-North direction since Cenozoic.During the compression and shortening, extensional structure is developed in Qinghai-Tibet plateau.For the purpose of understanding formation extensional structure in compression environment, thermal stress field and displacement field by temperature rising is calculated in crust.The feature of thermal stress field is described.A rising in temperature in lithosphere may cause very substantial tensile stress in shallow and compression stress in deep crust.Considering stress field caused by combined effect of northward push from Indian plate, gravity and thermal stress, tectonic deformation features in Qinghai-Tibet plateau can be understood better.