Surface passivation via post-treatment with organic reagents is a popular strategy to improve the stability and efficiency of perovskite solar cell.However,organic passivation still suffers from the weak bonding between organic chemicals and perovskite layers.Here we reported a facile inorganic layer passivating method containing strong Pb-S bonding by using ammonium sulfide treatment.A compact PbSx layer was in-situ formed on the top surface of the perovskite film,which could passivate and protect the perovskite surface to enhance the performance and stability.Our novel inorganic passivation layer strategy demonstrates great potential for the development of high efficiency hybrid and robust perovskite optoelectronics.