The　heat　and　flow　characteristics　of　mist/steam　two-phase　flow　in　U-shaped　internal　cooling　passage　of　gas　turbine　blade　are　studied　numerically　in　this　paper.　The　standard　k　-　model　was　used　as　the　turbulence　model　combined　with　the　DPM　model　to　calculate　the　influence　of　mist/steam　mass　ratio　and　mist　diameter　on　flow　and　heat　transfer　of　U-passage　with　different　shaped　ribs.　The　result　indicates　that　under　the　same　working　condition,　the　U-shaped　channel　with　45　deg.　V-shaped　ribs　has　better　heat　transfer　performance　than　other　channels　and　heat　transfer　non-uniformity　of　the　U-shaped　channel　with　75　deg.　ribs　is　the　worst　among　all　channels　studied　in　this　paper.　The　heat　transfer　performance　of　the　U-shaped　channel　with　V-shaped　ribs　is　higher　than　that　of　the　channel　with　paralleled　ribs.　As　for　the　mist/steam　cooling　in　U-shaped　passage　with　same　ribs　structure,　heat　transfer　non-uniformity　increases　with　the　increasing　of　heat　transfer　performance.　When　mists　diameter　increases　from　5μm　to　15μm,　the　heat　transfer　performance　of　the　Second-Flow-Passage　increases　obviously　and　the　heat　transfer　non-uniformity　increases　at　the　same　time.　The　heat　transfer　performance　has　not　been　further　enhanced　when　the　mists　diameter　continuously　increases　after　mist　diameter　are　larger　than　10μm.　Copyright　©　2018　ASME