Abstract: Simulation of 3D unsteady stator/rotor interaction in turbine stage with bowed and straight vane was presented in this paper.The effect of blade bowing on aerodynamic parameters especially on efficiency was studied in detail.The difference between 3D wake structure and wake mixing process in bowed and that in straight vane stage was discussed.The effect of blade bowing on the inlet condition of rotor was also studied.Efficiency and mass flow fluctuation phenomena and their effects on stage performance were described in detail.Based on the comparison between instant and average efficiency,the contribution of blade bowing to loss reduction in stator and rotor was also studied.