The Three Gorges power plant is large in both generator capacity and unit numbers. Due to the complex of the unit’s auxiliary system and its strong dependence on the plant auxiliary power, any breakdown or disturbance of the plant auxiliary power will lead to abnormal operation of the unit’s auxiliary system, subsequently affecting the operation of the main generator units. In the meantime, due to the long construction period of the Three Gorges project, the plant auxiliary power system was incomplete at the initial commissioning stage and low in reliability, which led to frequent trips and outage of generator units. Many measures have been taken, such as improving the unit’s auxiliary systems and control circuit, increasing the exit on-offs of generator units for improving the flexibility of generator’s power supply system, building the self-supply power plant for the Three Gorges power plant, and perfecting the plant auxiliary power network, and as a result, the power plant’s reliability has significantly improved in auxiliary power and the generator unit’s operation .