The　chemical　constituent　of　corrosion　product　scale　on　29Cr　super　duplex　stainless　cast　steel　after　electrochemical　polarization　in　artificial　seawater　was　studied　by　X-ray　photoelectron　spectroscopy　in　this　paper.　The　results　indicate　that　the　corrosion　is　mainly　pitting　corrosion;　MoO2-4,　NH+4　and　a　small　amount　of　NO-3　absorbed　on　the　surface　of　the　passive　film　so　that　to　enhance　the　protectiveness　of　the　layer.　The　outer　portion　of　passive　film　of　29Cr　super　duplex　stainless　steel　is　mainly　composed　of　hydroxide　type　compounds　such　as　Cr(OH)3,　FeOOH　and　oxides　such　as　Cr2O3,　Fe3O4,　FeO,　Fe2O3,　MoO2,　MoO3　and　NiO,　but　its　inner　portion　is　mainly　composed　of　abundant　metallic　elements　of　Fe,　Cr,　Ni,　Mo　and　oxides　including　Cr2O3,　Fe3O4,　FeO,　MoO2,　NiO　and　some　nitride　such　as　Cr2N.　During　the　passivation　process,　Cr2N　tends　to　enrich　at　the　passive　film　surface,　thereby　its　pitting　corrosion　resistance　may　be　enhanced.