Abstract: According to the design method of a typical three dimensional supersonic intake,a kind of three dimensional flow-path of a ram-rotor was designed.The three dimensional Reynolds-averaged Navier-Stokes equations and the Spalart-Allmaras turbulent model were adopted to simulate numerically the flow field of the designed three dimensional flow-path of the ram-rotor.It has been found that,unlike the linear shock wave system in three dimensional supersonic intake,the shock wave in the three dimensional flow-path is curved shock wave.As compared to the two dimensional flow-path,the shock wave system in the three dimensional flow-path is more vaguer and complex.The back pressure and the rotational speed have great influence on the performance of the three dimensional flow-path.