Abstract: The unsteady 3-D flow fields in a transonic compressor at design point were simulated numerically to study the effects of the swept and bowed rotors on the stage efficiency fluctuation.The results show that,as compared to the baseline,the time-averaged efficiency of the compressor with bowed and swept rotors is increased remarkably,and the amplitude of the efficiency fluctuation is obviously reduced.And the phases of the stage efficiency fluctuation waves in time are shifted.The bowed and swept rotors reduce the separation loss of hub and tip region and also lower the efficiency fluctutiaon amplitude thereto.