The Weis-Fogh mechansim is quite attractive because it can generate very high unsteady lift. It is indicated that the high unsteady lift is related to the attached vortex around the leading edge and trailing edge of wing/airfoil, which is caused by the relative motion. In the present work, the numerical results prove that, when the axial spacing is reduced, the interaction between rotor/stator can generate unsteady vortex around the rotor blades, and the rotor lift coefficient is increased, which improves the performance of stage. Besides reducing the axial spacing, the rotor/controllable stator system is proposed to apply vortex lift in turbomachinery. It is indicated that unsteady lift coefficient is increased greatly by the relative motion of rotor/controllable stator and the unsteady vortex is very important.