With　the　rapid　development　of　all-inorganic　CsPbX3　(X　=　I,　Br,　and　Cl)　perovskite　light-emitting　diodes　(PeLEDs),　their　external　quantum　efficiency　(EQE)　has　made　great　progress　in　the　last　few　years.　However,　severe　performance　degradation　at　the　operation　condition　impedes　its　large-scale　industrial　application.　In　this　text,　by　using　the　advanced　spherical　aberration　corrected　transmission　electron　microscope　(TEM),　the　degradation　pathway　of　PeLEDs　under　bias　loading　was　more　systematically　and　comprehensively,　especially　from　the　viewpoint　of　its　microstructural　evolution　pathway,　which　showed　that　iodine　vacancy　migration　triggered　the　structural　collapse　was　the　primary　inducement　of　performance　decay.　To　solve　this　problem,　inorganic　termination　ZnI2　was　employed　to　passivate　the　surface　halide　vacancy　defects　and　supplement　the　halide　ion　into　the　lattice,　which　significantly　improves　the　photoluminescence　(PL)　lifetime　and　stability　of　CsPbI3　quantum　dots　(QDs).　As　expected,　not　only　the　EQE　of　PeLEDs　has　been　greatly　improved,　but　also　the　operating　half-lifetime　is　enhanced　by　about　4　times　as　compared　with　the　original　one.　Microstructural　characterization　and　density　functional　(DFT)　calculations　confirm　that　the　preferential　segregation　of　Zn　element　on　the　surface　of　QDs　was　the　principal　cause　to　passivate　the　defect　state　of　QDs,　which　exhibits　lower　formation　energy　and　better　operational　stability.