This　study　numerically　examines　the　effect　of　actual　gas　turbine　operating　conditions　on　heat　transfer　characteristics　in　a　ribbed　passage　with　mist/steam　cooling.　A　60　degrees　ribbed　passage　with　aspect　ratio　of　1/1　was　investigated　at　Reynolds　number　of　300,000,　and　steam　cooling　was　used　to　provide　a　contrast.　Three　main　factors　were　considered:　coolant　temperature,　operating　pressure,　and　wall　heat　flux　density.　The　heat　transfer　enhancement　mechanism　of　mist/steam　cooling　was　explored,　and　the　results　showed　that　the　heat　transfer　performance　of　mist/steam　cooling　was　superior　to　steam　cooling.　When　the　coolant　temperature　varied　from　300　to　500　degrees　C,　the　average　Nusselt　number　of　mist/steam　cooling　decreased　by　26.6%,　and　the　heat　transfer　enhancement　ratio　dropped　from　15%　to　10%.　As　operating　pressure　increased,　the　heat　transfer　performance　factor　of　mist/steam　firstly　increased　and　then　decreased.　At　an　operating　pressure　of　1.5　MPa,　the　heat　transfer　achieved　its　optimal　performance,　and　the　heat　transfer　enhancement　ratio　achieved　its　maximum　value　of　15.9%.　Larger　wall　heat　flux　density　provided　less　heat　transfer　enhancement.　When　the　heat　flux　density　increased　from　100,000　to　300,000　Wm(-2),　the　average　Nusselt　number　of　mist/steam　cooling　decreased　by　13.8%,　while　the　heat　transfer　enhancement　ratio　decreased　from　25.3%　to　12.6%.