To　investigate　the　cooling　of　the　blade　leading　edge　of　a　humidified　gas　turbine,　the　effects　of　inlet　Reynolds　number　and　humidity　ratio　of　moist　air　on　the　impingement　cooling　of　flow　and　heat　transfer　are　analyzed.　An　impingement　cooling　model　with　an　inlet　chamber,　a　row　of　circular　impingement　holes　and　an　impingement　cooling　chamber　is　established.　The　ANSYS　CFX　software　is　used　to　numerically　investigate　the　influences　of　inlet　Reynolds　number　and　humidity　ratio　of　moist　air　on　flow　and　heat　transfer　characteristics　of　impingement　cooling,　and　the　properties　of　the　flow　and　heat　transfer　are　summarized.　Following　the　numerical　results,　the　Nusselt　number　is　correlated　with　the　Reynolds　number　of　impingement　holes　and　the　Prandtl　number　to　obtain　the　heat　transfer　correlation　of　the　moist　air　impingement　cooling.　The　results　show　that　the　cooling　performance　of　impingement　cooling　improves　with　the　increasing　Reynolds　number　and　humidity　ratio.　After　the　impingement　jet　impacts　the　target　surface,　the　coolant　flows　along　the　wall　surface　and　forms　a　complex　vortex　structure　in　the　impingement　cooling　chamber.　When　the　inlet　Reynolds　number　increases,　the　heat　transfer　of　the　target　surface　is　enhanced　due　to　an　increasing　coolant　vorticity.　The　Nu　distributions　of　the　target　surface　for　dry　air　cooling　and　moist　air　cooling　have　little　differences　with　the　same　inlet　Reynolds　number,　but　the　value　of　Nu　for　moist　air　cooling　is　slightly　higher　than　that　for　dry　air　cooling　and　the　difference　increase　with　the　increasing　inlet　Reynolds　number.　The　coolant　mass　flow　decreases　with　the　increasing　humidity　ratio,　while　the　Nu　of　the　target　surface　increases　with　the　increasing　humidity　ratio.　The　heat　transfer　correlation　coincides　well　with　the　numerical　results　and　can　be　used　to　predict　the　heat　transfer　coefficient　of　moist　air　impingement　cooling.　©　2020,　Editorial　Office　of　Journal　of　Xi＇an　Jiaotong　University.　All　right　reserved.