The　ultrafine/nanostructured　WC-Co　composite　powder　was　synthesized　by　reduction　and　carburization　reactions,　and　then　Cr　was　added　to　the　powder　to　obtain　WC-10Co-4Cr　composite　powder;　afterwards,　the　WC-10Co-4Cr　composite　powder　was　agglomerated　to　prepare　the　composite　powder　feeding　that　was　used　in　spraying;　finally　the　ultrafine/nanostructured　WC-10Co-4Cr　coating　was　prepared　by　high　velocity　oxygen　fuel　(HVOF).　The　phases,　elemental　distribution　and　microstructure　of　the　coating　were　characterized　by　X-ray　diffraction　(XRD)　and　transmission　electron　microscope　(TEM),　and　then　the　wear　resistance　and　corrosion　resistance　of　the　coating　were　tested.　The　results　show　that　the　main　phase　of　the　coating　is　WC,　the　binding　phase　of　amorphous　structure　is　Co(Cr),　and　there　is　a　little　W2C　phase　of　hexagonal　crystal　structure　and　W2C+　Co(Cr)　multiphase　of　amorphous.　The　change　rule　of　WC　grain　was　obtained　from　phase　boundary　to　eutectic　area　to　Co　area　by　the　quantitative　analysis　of　distribution　of　Co　and　Cr　element　in　coating.　Combined　WC-10Co-4Cr　composite　powder　and　the　process　characteristics　of　HVOF,　we　explained　the　causes　of　Cr　distribution　in　the　WC-10Co-4Cr　coating,　and　discussed　its　influence　on　the　coating　performance.