The utility model discloses an oil -immersed transformer, including transformer frame, storage oil tank, transformer core, oil purifier and radiating fin, one side of transformer core is equipped with main heat dissipation frame, arranges on the main frame that dispels the heat and installs main radiator fan, and still install fan start control ware on the main heat dissipation frame, fan start control ware is connected with fan wind direction controlling means, installs main temperature sensor on the transformer core, and main temperature sensor is continuous with fan start control ware, fan wind direction controlling means can detect the wind direction of natural wind, when main temperature sensor determine is higher to the temperature of transformer core, send control signal through fan start control ware, start each main radiator fan, fan start control ware is according to the next wind direction signal of fan wind direction controlling means conveying simultaneously, each main radiator fan's of control rotation direction, make the air current syntropy that air current that main radiator fan produced with the natural wind as far as possible, and then the wind speed of avoiding main radiator fan is weakened, thereby guarantee radiating effect and radiating efficiency.