In order to investigate into the dynamic response of hydraulic-mechanical-electrical system (HMES) in hydropower station under disturbance, we established the Simulink models of main parts of HMES by the user-defined modeling function of MatLab/Simulink software, and further built a complete dynamic simulation model of the HMES in line with its basic structure and operating characteristics. By using the model, we simulated the dynamic response of HMES in isolated and grid-connected operation modes under various disturbances including load disturbance, power regulation disturbance, and short-circuit fault disturbance. The simulation results show that the proposed model could describe the dynamic responses of HMES under disturbances accurately. The model can be taken as a reliable simulation platform for studying the coupling mechanism of HMES and tuning of controller parameters.