The invention provides a servo mechanism dynamic characteristic analysis method. The internal sensitive rigidity of the servo mechanism is identified through a planning and grading modal test; the finite element model is reasonably simplified; through verification of impact test frequency analysis and dynamic response, the accuracy and effectiveness of the finite element model are effectively proved, finally, the dynamic response of the servo mechanism in the water outlet process is calculated based on a time domain response analysis method, the fault mechanism is revealed according to the calculation result in combination with the impact brittle fracture related theory, and provides a reference basis for the subsequent structural design improvement.