Abstract: Discharge coefficients of film cooling holes on the turbine blade surface were measured in a large scale low speed turbine cascade.Discharge coefficients of coolant injection were obtained in the region of Re∞=250,000～450,000,and BR=0.5～2.5.The influences of Reynolds numbers and blowing ratios on discharge coefficients were investigated.The results show that turbine blade surface film hole discharge coefficients are different greatly for different hole array positions.The distribution of discharge coefficients is mainly determined by blowing ratio for the same geometry.Film hole discharge coefficients were increased obviously with blowing ratio in the case of low blowing ratio.In the case of high blowing ratio,the discharge coefficients became a constant.