Abstract: The structural deformation of the Longmen Mountains, western Sichuan was initiated during the Indosinian, and underwent the polyphase progressive deformation from the Yanshanian to the Himalayan. These deformational processes became progressively younger in age from north to south and from west to east. The Longmenshan thrust fault zone is characterized by N-S stepping, E-W zoning and longitudinal layering. The highly deformation in the overthrust fault zone led to the poor preservation of oil and gas. The fault-fold zones in the frontal parts of the Longmen Mountains are considered to be favourable for the hydrocarbon accumulation and the formation of the structural oil pools because of the moderately deformational conditions.