Abstract: Computational fluid dynamics (CFD) with proper boundary conditions was used to compare the performance of different states for capacity of entropy production control, or decrease of the pressure loss. Numerical results show that the flow field in supersonic rotor-vane is complex, phenomenon of interference between oblique shocks is obvious. The expansion shock of rotor tail induces the secondary flow and enhances the mixing of two fluids of different energy at short distance. Comparing mixing by gas-shock with shear between two fluids, the effect of turbulence is weak, even ignorable. The position and shape of the vane, such as the tail part, leading edge, the height of leading part, has an important effect on the flow regimes and efficiency of ejector. The compression-ratio and entrainment-ratio of the ejector is in proportion to rev of rotor. The rotor and vane could be free rotary with proper setting angle of vane. Furthermore, investigation on flow mechanism and efficiency of ejector is given.