Abstract:The compression of the Qinghai-Tibet Plateau to the Sichuan Basin resulted in the formation of the Longmenshan fault zone and the uplift of its mountains. Based on the regional plate motion characteristics near Longmenshan Mountain and the mechanical properties of deep rock mass, evolution process of regional tectonic system in Longmenshan with a time span of 3.2 million years are simulated and reconstructed by FLAC3D. The results show that a fault zone is formed firstly under the action of plate movement. The through faults have a strong controlling effect on the uplift of the surface，when the fault passes through the surface, Longmenshan and the western Sichuan plateau continue to uplift, with an average uplift rate of about 1.38 mm/yr; the western Sichuan depression in the right of the Longmenshan fault zone has only a small uplift, and there is a large gap between them. The simulated topographic characteristics are basically similar to the current topographic features. Based on the simulation results and the measured data, the evolutionary process map of the formation of Longmenshan fault zone and its adjacent regional topography is drawn. It can be concluded that the formation of the fault zone is an inevitable result under the action of plate compression; The formation of regional tectonic system in Longmenshanis the result of the combined action of plate compression, surface erosion and sedimentation.