The Longmenshan thrust system consists of two major groups of structural styles according to the depth of their involvement: basement thrusts-compressional fault blocks; fold-thrust system in the cover. In cross-section, the Longmenshan structural belt is divided into 5 zones. The propagation of the Longmenshan thrust system is piggy-back due to pushing at the early stage and overstep due to gravity sliding at the late stage. Balanced cross-sections and palinspastic reconstruction reveal that the total sliding displacement of the thrust system amounts to 120 km. The tectonic evolution of the Tethys domain in western Sichuan has experienced 5 stages: continental break-up; ocean-continent subduction ; continent-arc collision; orogenic thrusting; uplift of western Sichuan.