The utility model relates to an auxiliary heat-radiating device of a transformer, mainly comprising a fan and a bracket, wherein the fan is fixed at the upper part of the bracket, the upper part of the fan is provided with blinds with 25 degrees horizontally, a cooling water pipe is arranged on the lower part of the bracket, and nozzles are arranged at the lower part of the cooling water pipe. The auxiliary heat-radiating device of the transformer is arranged at the bottom of a radiating fin of the transformer, when the fan is started, the blind is opened through blowing of the fan, when the fan is switched off, the blind can be closed automatically, and the fan and the blind are arranged with 25 degrees horizontally, the structure can prevent rain water from falling on the fan in rainy days, so as to prolong the service life of the fan. The cooling water pipe at the lower part of the bracket and the ground form a 45-degree angle, and six nozzles with diameters of 0.2mm are arranged at each of two sides of the cooling water pipe, so that the cooling water can be sprinkled on the ground evenly to reduce the surrounding temperature; when the fan is started, the cooling air with low temperature at the bottom part can be blown upwards to the radiating fin to effectively control the temperature of the transformer.