Located in the transitional position between Qinling Mountains and Sichuan Basin, the Daba Mountain nappe structure is composed of pull-apart basin, nappe zone, mobile belt, disturbed zone and main slide surface, with the mobile belt and the disturbed zone being favorable places for oil-gas accumulation. Based on computing and analyzing gravitational and magnetic data, the authors obtained the nappe distance of the nappe zone, and reached the conclusion that sedimentary strata of Sichuan basin may exist under the inferred nappe zone. The result is helpful to exploring oil-gas resources in Sichuan basin.