Forming large-size thin-walled hemispherical parts by hydroforming is often accompanied by serious wall thickness thinning, instability and rupture of the suspending area. In order to solve the appeal problems, this paper adopts the combination of finite element numerical simulation analysis and experimental verification, and takes the 6061-T6 aluminum alloy thin-walled hemispherical part as the research object to carry out the formability analysis of double-layer sheet hydroforming. In order to improve the accuracy of numerical simulation, uniaxial tensile tests of AA6061-T6 tensile specimens were carried out, and a BP neural network prediction model that can truly reflect the plastic deformation characteristics of materials was established. In this paper, the wall thickness and the contact status between punch and sheet are used as the evaluation indexes to simulate and analyze the hydroforming of the double-layer sheets, and the process flow of the single-sheet and the double-layer sheet hydroforming was compared and analyzed. The forming law of sheet metal under different friction coefficient between sheets and different upper sheet thickness was explored. Finally, the optimal process conditions were used for forming experiments, and the results were basically consistent with the simulation results.