According to aeromagnetic and gravitational data,the boundary and scope of Sichuan basin were determined based on the analyses of the characteristics of gravity and magnetic fields.And on the basis of compiling depth map of the metamorphic basement and structuring zoning map,the research has been conducted on the basin's basement structure,characteristics and features of depth change,structure framework,and caprock thickness.The research indicates that the metamorphic basement is composed of Proterozoic metamorphic series,and the buried depth of crystalline basement can reach to 5 000 to 20 000 meters.The caprock is the layers of Ediacaran,Paleozoic,and Mesozoic.The occurrence and development of the basin are restricted by near-northeast and northwest-west construction,which has a pattern of four depression and three uplifts.All these new cognitions and conclusions provide a reference for further oil and gas exploration in the basin.