Based on the comprehensive analysis of tectonic deformation,tectonically spatial distribution relation,fault plane occurrence change,tectonic stress field,etc.,it is considered that the Quaternary movement forms of the active fault zone along north margin of Mt.Altun underwent a gradual change process from compressional thrust through left-lateral strike-slip simultaneously with compressional thrust to pure left-lateral strike slip.Acting upon the change,evolution of regional tectonic stress field in the studied area is roughly divided into three stages during which the directions of compressive principal stress axes are near NS, NNE and NE in the order from the earlier to the later.The changes of tectonic stress field and fault movement form mainly are caused by the eastward slip of secondary block and eastward flow of lithospheric mass resulting from continuously northward push and pressure of the Indian plate.