According to the resonance mechanism, power system forced low frequency oscillations can be aroused by power disturbance of prime mover. Therefore, the causes of turbine power disturbance were analyzed. The coupling model between turbine-governing system and power system was established in MATLAB. The possibility of governing system disturbance inducing the variation of control valve position and turbine power was researched in detail. The simulation results indicate that high level variation of control valve can be induced by the rotor speed deviation disturbance, if the speed-droop ratio of turbine-governing system is too small in local running position; power system low frequency oscillations of resonance mechanism might be caused by the disturbance of rotor speed deviation, when it’s frequency is close to power system natural oscillations frequency. Oil-pressure pulsation is easily happened in hydraulic governing system. If the frequency of oil-pressure pulsation is near to power system natural oscillations frequency, power system low frequency oscillations of resonance mechanism can be induced.