Based on the study of the development and distribution of bitumen outcrops, filling  characteristics of fluids in different layers and tectonic deformation, an ancient oil and gas reservoir can be identified in the south section of Longmenshan Mountains, and the process of development and destruction of the ancient oil and gas reservoir is reconstructed. The research indicates that there is a great lot of bitumen to fill in the secondary vugs and fissures in the Devonian Guangwushan Formation and Sinian Dengying Formation. The abundant bitumen, stable extension and great thickness of bitumen infilling in Dengying Formation suggest that there is an ancient oil and gas reservoir in the south section of oft-com:office:smarttags" />Longmenshan Mountains.