Abstract: The mathematic model of the hydro-turbine governing system is established in a small disturbed motion range. A research using SIMULINK to analyze the dynamic characteristic of the hydro-turbine governing system with 1% frequency disturbance and 30% load rejection is carried out. The optimal governing parameters in the processes of frequency disturbance in which the transient rotational-difference coefficient bt is equal to 0.4 and the transient feedback time constant Td, 2.95 and of load disturbance in which bt equals 0.5 and Td,2.95 are all adjusted and the favorable dynamic characteristics in aspects of fastness and stability of the governing system are obtained by simulation. The results indicate that the model is convenient and flexible to simulate the hydro-turbine governing system using the SIMULINK software.