The invention relates to an oil-immersed transformer cooling system control method based on actual load. The method includes finding the position of a hottest area of a transformer in the operation process through an optical fiber temperature measurement system, and adjusting an on-off state of a cooling system around to control the internal temperature of the transformer in real time. According to method, load occasions in the transformer can be monitored in real time, the internal temperature of the transformer is smoothly adjusted based on distribution positions of hot points, and failures in the transformer due to high temperature or acceleration of insulation ageing are avoided.