This paper numerically investigates the effects of the film cooling hole diameter and the film cooling hole location on the impingement/effusion cooling performance inside a concave target channel. Three film cooling hole rows are established on the target surface under two arrangements. In the first arrangement, the inclined angle between the film cooling hole axis and jet hole axis is 0 degrees, -60 degrees, 60 degrees respectively. In the second arrangement, the inclined angle is 0 degrees, -30 degrees, 30 degrees respectively. In the first effusion hole arrangement, numerical simulations are conducted under three Reynolds numbers. In the second effusion hole arrangement, numerical simulations are only conducted under the middle Reynolds number. Four film cooling hole diameters of 0.4D, 0.6D, 0.8D, 1.0D are studied based on a fixed jet hole diameter of D = 10 mm. The heat transfer performance, pumping power and overall performance are evaluated and compared. Effusion air distribution and static pressure distribution are analysed. Flow development inside the target channel is compared and discussed. Nusselt number distribution is evaluated and compared. Results show that the effusion air mass flow rate and the flow development inside the target channel are obviously affected by the film cooling hole diameter and film cooling hole location. The heat transfer performance is also significantly affected by the film cooling hole diameter and film cooling hole location. (C) 2019 Elsevier Ltd. All rights reserved.