A　multi-physic　fields　coupling　mathematical　model　was　established　using　fluid　controlling　equations,　heat　and　mass　transfer　equations,　species　transport　equations　and　Maxwell＇s　electromagnetic　equations,　to　discuss　the　flow　field　characteristics　inside　and　outside　plasma　gun.　The　ionization　and　recombination　reactions,　as　well　as　the　effect　of　non-local　thermal　equilibrium　were　taken　into　consideration　to　investigate　the　plasma　flow.　On　this　basis,　the　new　three　dimensional　model　was　adopted　to　analysis　the　distribution　of　particles＇　velocity　and　temperature.　The　relative　error　was　less　than　10%　comparing　with　measured　value　by　DPV2000　diagnosis　system.　In　addition,　both　particles＇　velocity　and　temperature　achieved　maximum　at　the　distance　of　70-90　mm,　this　range　can　be　selected　the　best　spraying　distance.　The　analysis　of　flight　particles　in　the　plasma　flow　will　lay　the　foundation　for　study　particles＇　deposition　and　flattening　on　substrate,　and　provide　theoretical　guidance　for　optimization　of　process　parameters　and　gun　structure.　©,　2014,　Zhejiang　University.　All　right　reserved.