Considering the nonuniformity of the flow characteristics in the holes under real conditions, a supersonic film-cooling model of discrete holes fed by a stagnant plenum is established in the present study. A large-eddy simulation of film cooling with single-row cylindrical holes and fanshaped holes was carried out under a freestream Mach number of 1.4. The film cooling effectiveness and flow mixing structure at different blowing ratios were compared and discussed. The simulation results show that there is no obvious jet lift-off near the hole outlet when the blowing ratio is small due to the weak momentum characteristics of the jet. Under the action of supersonic freestream pressure, the upstream region presents highly effective film characteristics; however, the mixing degree of the jet and the freestream is intensified along the downstream development process. With the increase in the blowing ratio, the development along the flow direction gradually shows a change pattern of first increasing and then decreasing. The downwash vortex pair near the normal wall is the main factor affecting the insufficient extension effect of the discrete-hole film in the supersonic freestream, and the jet is constrained by the joint coupling of the horseshoe vortex induced in front of the hole and the reverse counter-rotating vortex induced by the center vortex pair. The lateral spreading angle can effectively enhance the spanwise film-coverage range of discrete holes, while it is not enough to improve the film extensibility in the flow direction.