The ionic defects in hybrid halide perovskite materials served as the recombination center severely restricts its application for solar cells.Here,we proposed a dual-passivation strategy via simply incorporating low-cost ammonium chloride to simultaneously passivate negative-and positive-charged ionic defects,as indicated by first-principles density functional theory calculation.The efficient defect modulation reduces the defect density and prolongs the carrier lifetime,thereby contributing to the highly crystalline perovskite,which is demonstrated by light-dependent kelvin probe force microscopy,transient absorption and visualized fluorescence lifetime imaging microscopy.Benefiting from these merits,the power conversion efficiency of perovskite solar cells is boosted up to 21.38%.More importantly,this dual-passivation approach can be further extended to mixed-cation perovskite systems,not limited in traditional methylammonium based perovskite only.Such methodology of simultaneously regulating ionic defects in different types may probably give impetus to effectively promote perovskite evolution.