In this paper, organic-inorganic hybrid perovskite (MAPbI3) optical absorption layer thin film with different thickness was prepared by controlling the concentration of PbI2(DMSO) solution by two-step method, and a large area perovskite solar cell based on carbon electrode hole-free transport layer was assembled. The crystal phase, optical absorption properties, surface morphology and elemental composition of MAPbI3 optical absorption layer films with different thickness were analyzed, and the photovoltaic performance of perovskite solar cells prepared based on MAPbI3 film were further tested. The results show that the thickness of MAPbI3 photoabsorption layer is positively correlated with the concentration of PbI2(DMSO). The thickness of MAPbI3 optical absorption layer prepared by 1.3 mol/L PbI2 solution is about 350 nm, which has good crystallinity and optical absorption intensity, and the surface of the film is compact and smooth without obvious defects. Finally, the perovskite solar cell based on 350 nm MAPbI3 optical absorption layer achieves 8.48% photoelectric conversion efficiency.