Abstract: In this paper,MA₃Bi₂I₉ solar cells are prepared by low-pressure vapor assisted solution process（LP-VASP）. Through this process,films with grain sizes of 300 nm and low roughness are acquired,and the absorption edge position is at 598 nm with optical absorption band gap of 2.07 eV. In addition,compared with the films prepared by one-step solution process or two-step solution process,the MA₃Bi₂I₉ perovskite films prepared by LP-VASP possess compact,large-grained surfaces which are different from the films prepared by the other two methods. It is found that the films prepared by LP-VASP effectively inhibit the carriers recombination,and the carrier internal fluorescence lifetime of the films is increased from 7.17 ns to 8.81 ns. The best efficiency is 0.178%,which is twice the efficiencies of the solar cells prepared by the other two methods.