Abstract: The purpose is to reveal the vibration of the rotor system of centrifugal pump in case of coupling parallel misalignment. Firstly,the rotor system components are simplified,and the finite element model of the rotor system is established. Then,the influence of different parallel misalignment on the vibration characteristics of centrifugal pump rotor system is studied through a comparative analysis of vibration displacement spectrum diagram and axis orbit diagram. The results show that the ideal centering rotor system is dominated by radial vibration,the radial vibration frequency is 1 time of the rotation frequency,the axial vibration frequency is 1 time of the blade passing frequency,and the axis orbit is elliptical;the coupling parallel misalignment causes a large radial vibration of the shaft on the rotor system and the vibration characteristic frequency shows an obvious 2 APF. The vibration amplitude increases linearly with the increase in the parallel misalignment;the axis orbit of the rotor system with the parallel misalignment shows a banana shape.