Abstract The discharge coefficient of laidback fan-shaped holes on turbine blades is investigated using experimental and numerical simulation methods. The study is conducted on a linear cascade, with single rows of film holes set on both the pressure and suction surfaces of the test blade, coolant supplied by an internal crossflow channel. The crossflow Reynolds number ranged from 39100 to 78200, and the pressure ratio ranged from 1 to 1.5. This research considered the effects of crossflow Reynolds numbers, hole length-to-diameter ratio, and hole row position on the discharge coefficient of film holes. The findings are as follows: internal crossflow increases the inlet loss of film holes and flow separation within holes, leading to a significant reduction in the discharge coefficient of film holes. Meanwhile, film holes on the pressure surface of the blade exhibit greater sensitivity to crossflow. Under different hole length-to-diameter ratio conditions, the length of the cylindrical section is the primary factor affecting the discharge coefficient, the magnitude of the discharge coefficient depended on the extent of flow separation within the cylindrical section. The sensitivity of the discharge coefficient to variations in the cylindrical section length decreases once cylindrical section length exceeds 2.8D for the pressure surface and 2.0D for the suction surface, where the inlet separation region reattaches to the wall. The hole row positioning has a significant impact on the discharge coefficient in the plenum condition, especially under conditions where the pressure ratio is less than 1.05.