The film cooling characteristics of the transverse trench (TT) and the double-wave trench (DWT) were numerically studied by using Reynolds-averaged Navier–Stokes simulations with realizable k–ɛ turbulence model and enhanced wall treatment. The experiment was used to validate the accuracy of numerical simulation. The film cooling effectiveness and the heat transfer coefficient and the heat flux ratio of the double-wave trench are investigated, and the distribution of temperature field and flow field were analyzed. The results show that the double-wave trench can effectively improve the uniformity of jet compared with the transverse trench. The anti-counter-rotating vortices which can press the film on near-wall are formed at the downstream wall of the double-wave trench. With the increase of the blowing ratio, the span-wise averaged heat transfer coefficient of the double-wave trench increases. The span-wise average heat flux ratio of the trench width W = 1.4D condition is lower than that of the other two trenches, so it has the best thermal protection effect of film cooling on the wall.