Abstract: Taking the pump-turbine of a pumped-storage power station in China as the research objective,the unsteady flow characteristics of the full-flow channel of the asynchronous guide vane under different arrangements is calculated simulatively by using the SST k-ω model. The simulation results are compared and verified with the experimental results. The inflow characteristics of the runner and the guide vane in different arrangements are discussed. The force of the runner and the pressure pulsation of the draft tube are analyzed quantitatively in different arrangements. The results show that the asynchronous vanes are damaged to varying degrees in the high-speed water ring vaneless region under different arrangements,and the degree of damage has a great relationship with the number and arrangement of asynchronous vanes. The peak-to-valley difference of resultant of forces of the radial force-combination is continuously increasing,and the curve closure degree of the resultant of forces of radial force is also increasing with the increase of the asynchronous vanes number;the relative amplitude of the pressure fluctuation of the draft tube pressure is obviously smaller and improved. The cross-section pressure of the draft tube is also decreased and the eccentricity of the draft tube vortex is reduced.