When the power supply is normal during the operation of the wind turbine, the pitch system relies on the mains power supply. In order to ensure that the pitch system can still work for a period of time after the mains power is stopped, so as to ensure that the unit can be safely shut down in case of serious fault or major accident (blade feathering to 90 degrees). An energy storage device is needed to provide certain working energy for the system. At present, energy storage devices in wind power industry use batteries, which have the main disadvantages of heavy weight, large volume, short cycle life and high maintenance cost. At the same time, the charge discharge efficiency is low and the working temperature is strict. Because of its excellent characteristics of fast charge and discharge and long cycle life, super capacitor is very suitable for energy storage device of wind turbine pitch system, which can effectively enhance the reliability of pitch system.