In　the　preparation　of　Sn-Pb　alloyed　perovskite,　a　large　amount　of　stannous　fluoride　(SnF2)　additive　is　often　employed　to　inhibit　the　oxidation　of　Sn2+　ions.　However,　excessive　SnF2　deteriorates　quality　of　the　film,　photoelectric　conversion　efficiency　(PCE)　and　stability　of　the　device.　Therefore,　the　development　of　new　antioxidants　at　low　doses　is　essential　to　achieve　high-performance　Sn-Pb　alloyed　perovskite　solar　cells.　In　this　study,　a　two-step　process　was　used　to　prepare　Sn-Pb　alloyed　perovskite　film.　In　the　first　step,　low-dose　stannous　iso-octanoate　(SnOct2)　was　introduced　to　replace　SnF2　to　inhibit　the　oxidation　of　Sn2+.　This　study　showed　that　the　additive　could　improve　the　crystallization　quality　of　the　film,　and　the　average　grain　size　of　the　film　with　SnOct2　could　reach　850　nm　while　the　amount　of　grain　boundaries　was　reduced.　The　film　with　the　addition　of　SnOct2　still　contained　93.5%　Sn2+　after　storage　for　7　d　in　the　glove　box.　And　due　to　the　excellent　oxidation　resistance　of　SnOct2,　the　device　with　the　additional　SnOct2　had　a　lower　defect　state　density,　which　was　reduced　from　7.20×1015　to　4.74×1015　cm–3,　inhibiting　the　non-radiative　recombination.　In　addition,　SnOct2　improved　the　surface　energy　levels　of　perovskite　films.　Finally,　PCE　of　Sn-Pb　alloyed　perovskite　cell　supplemented　with　0.030　mmol　SnOct2　reached　17.25%,　superior　to　that　of　device　supplemented　with　0.10　mmol　SnF2　(11.63%).　After　storage　in　nitrogen　for　50　d,　more　than　70%　of　initial　PCE　was　still　preserved.　©　2024　Science　Press.　All　rights　reserved.