Abstract: The second member of Xujiahe formation is the main gas reservoir in western Sichuan. Based on diagenesis, sedimentation and tectonism, the main controlling factors which can affect reservoirs from the aspects of rock type, rock pore, sedimentary microfacies, constructive diagenesis, destructive diagenesis, structural form and tectonism have been discussed in this paper. The conclusion believes that grain grade and quartz can provide a better condition for the reservoirs, the constructive diagenesis before gas accumulation can improve the reservoir property, and high angle fracture formed in late-stage tectonism is the guarantee of getting industrial gas reservoir in this area.