Abstract: In order to improve the reliability of liquid rocket engine and prevent destructive failure,coupling between the rotating speed frequency and the gas pressure impulse must be avoided.Vibration responses of the turbopump were analyzed by building a transmission model of the excitation.The result that the gas pressure impulse of the gas generator is the main source of the excitation was given.Then,the coupled rules between excitation and rotating speed frequency of the turbine disk were shown and the coupled rotating speed range was obtained.In the end,the calculation results were validated by hot test information of the liquid rocket engine.