An abnormal vibration problem exists in the hydrogen turbine pump in rocket engine,which is caused by the influence of the labyrinth seal used in the turbo pump on the stability of the pump’s rotor system.In order to solve the vibration problem,the rotor system model was established.Dynamic coefficient of seal and inducer was calculated by CFD and was generated into the rotor system model to obtain rotor logarithmic decrement.The influence of labyrinth seal and inducer on the stability of rotor system was studied.The influence of holepattern seal instead of labyrinth seal on the stability of rotor system was analyzed.The results show that a relatively large rotor logarithmic decrement can be obtained by the labyrinth seal with small eccentricity,big sealing clearance,suitable tooth thickness and multiple teeth of labyrinth seal.However,it is still unable to meet the requirement of the logarithmic decay rate greater than 0.1 in API617 standard.The use of holepattern seal instead of labyrinth seal can meet the requirement of API617 standard,and the the stability of rotor system is improved greatly.The research also shows that the inducer has a negative effect for the stability of rotor system.