Abstract: The film cooling characteristics of blade surface were numerically investigated using the two-equation turbulence model of the renormalization group.Three-dimensional turbulent flow in turbine cascade and the cooling effectiveness on blade surface were studied under different Reynolds numbers and blowing ratios.The influence of the cooling effectiveness of cylindrical film cooling holes on the blade suction surface with varying location was investigated.Results show that the cooling effectiveness for each film cooling hole increases with the increment of the mainstream Reynolds numbers.The cooling effectiveness downstream the exit of holes changes obviously with the increment of blowing ratio,and away from the downstream the effectiveness keeps increasing with the increment of blowing ratio.Under the same condition the cooling effectiveness of location 1 was higher than other two locations.