Abstract: To study the influence of clocking effect on the performance of multi-stage centrifugal pump,the RNG k-ε turbulence model was used to simulate the flow field in the two-stage centrifugal pump under different guide vane clocking positions. Six schemes were designed for one time position when the secondary guide vane relative to the primary guide vane was rotated with clockwise 10 degrees. The results indicate that under the design flow rate,compared with that of no clocking scheme,when the clocking angle of the second guide vane is half of the angle between the guide vanes,the increase of the pump head and efficiency reaches the maximum value,up to 0.18% and 0.16%,respectively. With the increase of flow rate,the influence of clocking effect of guide vanes on pump performance gradually increases. With the increase of the clocking angle of the secondary guide vane,the dominant frequency amplitude of pressure fluctuation at each monitoring point first decreases and then increases. When the staggered angle of the first and second guide vanes is 30°,the amplitude of the dominant frequency amplitude of pressure fluctuation reaches the minimum,which is 34.3% lower than that of the no clocking scheme. The change of the clocking position can effectively reduce the interstage vortex area and intensity,thereby reducing the intensity of the pressure fluctuation in the pump.