The invention relates to the technical field of fire-fighting equipment, in particular to a power transformer fire extinguishing system and a control method. The power transformer fire extinguishing system comprises an equipment protecting room, a fire extinguishing pipe network, multiple fire detectors, point spraying branch control pipe valves and weatherproof porous bundling nozzles; a gas cartridge set, a starting bottle set, a 3D boiling powder storage tank and a fire extinguishing controller are arranged in the equipment protecting room, and the fire extinguishing controller is provided with a multi-feature signal detector, an air speed detector and a reburning detection and alarm controller. The control method comprises the following steps of initialization, fire detection, alarm and fire extinguishment; the fire extinguishment comprises the steps of point fire extinguishing scheme generating, multi-point fire extinguishing scheme generating and full fire extinguishing scheme generating. According to the power transformer fire extinguishing system and the control method, the main pipe network is buried under a terrace, the safety is high, and the stable reliability of the fire extinguishing system is guaranteed; a point fire extinguishing scheme, a multi-point fire extinguishing scheme and a full fire extinguishing scheme are designed according to different fire types, and the fire extinguishing efficiency and the fire extinguishing effect are greatly improved.