Abstract: The compound helicopter has gained more and more attention so far since there is an efficient way to improve the performance of such helicopter.By employing the free-wake arithmetic and vortex lattice method(VLM),a program for the rotor-wing system of compound helicopter aerodynamic computation has been developed.With this program,interactions between the rotor and the wing in different advance ratios were computed.Some conclusions can be made from the computation results: for the compound helicopter described in the paper,the influence of wing on the rotor lift is small,but a little bigger on the rotor torque;with the increase of the flight speed,the influence of rotor on the wing decreases;and the interaction reduces the efficiency of both the rotor and the wing.