In　this　paper,　the　effect　of　Er　element　on　ignition-proof　property　of　Mg-Zn　alloys　was　studied.　XRD,　SEM　and　EDS　were　used　to　investigate　the　ignition-proof　performance　and　the　oxidation　film　of　the　alloys.　The　element　of　Er　tended　to　enrich　in　the　surface　of　molten　magnesium　alloys　during　the　oxidation　process.　And　the　oxidation　film　was　composed　of　MgO　and　Er2O3.　With　the　Er　content　in　Mg-Zn　alloy　increasing,　the　content　of　Er2O3　in　oxidation　film　increases　and　the　ignition　point　of　Mg-Zn　alloys　rise.　So　Er　can　improve　the　ignition-proof　properties　of　Mg-Zn　alloys　greatly.