Numerical　method　is　applied　to　analyze　the　spraying　process　using　supersonic　spraying　gun;　special　attention　is　paid　to　temperature　and　velocity　fields　of　argon　plasma　flow,　including.　In　term　of　plasma　properties,　ionization　and　recombination　of　plasma　species　are　taken　into　consideration.　The　impact　of　internal　injection　channel　on　main　plasma　gas　flow,　both　velocity　and　temperature,　are　investigated.　With　full　dimensional　model,　three　dimensional　properties　of　plasma　flow　and　internal　injection　channel　impact　are　revealed.