Abstract: In the paper,potassium acetate（KAc）is used to modify the SnO₂electron transport layer,thus regulating the energy level alignment of the SnO₂/perovskite interface. In addition,the introduction of KAc film passivates perovskite film to attenuate the probability of non-radiative recombination and inhibits the bulk and interface charge recombination. Meanwhile,the introduction of KAc film improves the growth process of perovskite crystals. Perovskite films with grain size increase from 450 nm to about 600 nm and without pinholes are produced. Therefore,inserting KAc as the modification layer significantly reduces the defect of the SnO₂electron transport layer and optimizes energy level difference as well. As a result,the efficiency of the optimized solar cell is increased by 7.63%compared with that of the referred device,and the IPCE is increased from 87.3% to 90.1%.