Abstract: Took Longmenshan regional kinematic characteristics and mechanical characteris-tics of deep rock mass as basic condition, we used FLAC simulation software to analyze geomorphic process of Longmenshan fault and the crustal stress evolution mechanism of its adjacent area. The results show that regional plate motion was the important reason of the Longmen- shan landforms formation, and the relative slip velocities of three faults in Longmenshan are 1.53, 0.245 and 0.458 mm/a respectively, which basically coincide with the actual monitoring results. The left region of Longmenshan fault zone is uplifted, while the right region that is the Sichuan basin remains stable. With the regional plate motion, there are three stages in the development of principal stress near the fault zone, which are the low-state stability stage, the increase stage and the high-state stability stage, and balance of stress accumulation-stress release is finally formed. The ratio of maximum and minimum principal stress near the fault zone is in a range of 2.94—3.71, and the average value is 3.3, basically coincide with the actual monitoring results. The following conjecture can be obtained that Longmenshan fault and its vicinity area will be in a high deviatoric stress environment for a long time, and will under the seismic period of " stress accumulation-entering the critical state-earthquake generation-new stress accumulation” for a long time.