Heat　transfer　and　film　cooling　performance　on　the　rotor　blade　tip　were　investigated　by　solving　the　Reynolds　averaged　Navier-Stokes　(RANS)　equations.　At　three　different　tip　clearances　(1.31　mm,　1.97　mm　and　3.29　mm),　two　kinds　of　cooling-hole　distributions　(single-hole　array　located　at　the　camber　line　and　two-hole　array　located　at　the　camber　line　and　near　pressure　side)　and　two　blowing　ratios　(1　and　2),　heat　transfer　coefficient　and　film　cooling　effectiveness　were　numerically　evaluated　and　compared　with　the　existing　experimental　data.　The　results　show　that　for　the　cooling-hole　array　located　at　the　camber　line,　coolant　injection　can　effectively　cool　the　pressure　side　of　the　squealer　tip　region.　Moreover,　as　the　blowing　ratio　increases,　the　high　heat　transfer　coefficient　area　on　the　squealer　tip　shrinks　near　the　leading　edge　suction　side,　and　a　lower　heat　transfer　coefficient　near　the　pressure　side　of　the　squealer　tip　can　be　achieved　as　well.　However,　the　film　cooling　effectiveness　near　the　pressure　side　of　the　squealer　tip　increases　significantly.　As　the　tip　clearance　increases,　the　high　heat　transfer　coefficient　area　extends　from　the　suction　side　to　the　pressure　side　near　the　leading　edge,　and　the　averaged　heat　transfer　coefficients　on　the　squealer　tip　increase　as　well.　However,　the　film　cooling　effectiveness　near　the　pressure　side　and　trailing　edge　decreases.　For　the　case　with　two　cooling-holes　array,　coolant　injection　from　the　pressure　side　can　effectively　cover　the　squealer　rim　and　blade　trailing　edge,　and　enhance　the　cooling　effectiveness　near　the　pressure　side　of　the　squealer　tip.　As　the　blowing　ratio　increases,　heat　transfer　coefficients　near　the　pressure　side　and　on　the　squealer　rim　and　blade　trailing　edge　decrease　obviously　while　the　film　cooling　effectiveness　at　these　regions　increases　significantly.　As　the　tip　clearance　increases,　the　high　heat　transfer　coefficient　area　extends　from　the　suction　side　to　the　pressure　side　near　the　leading　edge.　And　the　heat　transfer　coefficients　near　the　pressure　side　of　squealer　tip,　on　the　squealer　rim　and　on　the　blade　trailing　edge　increase　significantly　while　the　film　cooling　effectiveness　decreases.　©　2016,　Editorial　Office　of　Journal　of　Xi＇an　Jiaotong　University.　All　right　reserved.