Using　mist/steam　two-phase　flow　by　mixing　a　small　amount　of　fine　water　droplets　into　steam　as　the　working　fluid　for　the　internal　cooling　passages　of　blades　and　vanes　is　a　promising　cooling　technology　for　future　gas　turbines.　We　proposed　a　new　cooling　channel　roughed　with　the　column-row-ribs　to　achieve　higher　cooling　efficiency　and　better　heat　transfer　uniformity.　The　heat　transfer　experiment　was　conducted　to　validate　the　effectiveness　of　our　numerical　method.　Flow　and　heat　transfer　performance　of　mist/steam　two-phase　flow　was　investigated　in　channels　of　different　gap　ratios　and　in　a　column-row-ribbed　channel　with　gap　ratios　of　Ε=0.177　under　different　working　conditions.　Comparing　to　the　solid　ribbed　channel,　the　column-row-ribbed　channels　sacrifice　the　heat　transfer　performance　to　achieve　better　heat　transfer　uniformity.　As　Ε　larger　than　0.264,　the　column-row-ribs　have　better　thermal　enhancement　performance　than　the　solid　ribs.　For　the　column-row-ribbed　channel　with　gap　ratio　Ε=0.177,　the　heat　transfer　effect　increases　with　the　Re　number.　But　the　thermal　uniformity　and　the　thermal　enhancement　of　the　channel　decreases　obviously.　As　the　wall　heat　flux　q　rises　from　3000W/m2　to　40000W/m2,　the　thermal　enhancement　factor　F　gradually　increases.　But　the　wall　heat　transfer　becomes　less　even.　Continuously　increasing　the　mist/steam　mass　ratio　will　help　to　increase　the　heat　transfer　effect　of　the　heated　walls,　so　does　the　heat-transfer　non-uniformity.　Simply　increasing　the　droplets　diameter　will　decrease　the　thermal　enhancement　factor　and　increase　the　heat　transfer　non-uniformity　at　the　same　time.　©　2020　Elsevier　Ltd