Abstract: The Effects of hole shapes,secondary flow Reynolds numbers,and blowing ratio on the heat transfer downstream of film cooling holes have been investigated.Experiments on dust-pan shaped holes,cone-shaped holes and round holes have been conducted with secondary flow Reynolds number ranging from 10,000 to 25,000 and blowing rate ranging from 0 3 to 2 0.Measurements are taken for 26 conditions.Results show that the critical blowing ratio is 1 3 for the dust-pan shaped holes and cone-shaped holes,0 7 for the round holes.The turbulence provided by jet from round holes is greater than that from dust-pan shaped holes and cone-shaped holes.