The forced oil circulating air cooler for transformers is a type of high-efficiency and energy-saving product optimized according to JB/T8315-1996and other similar internal product structures. The loss of the auxiliary machine is about 2.5% of the cooling capacity. The material of the cooling pipe is pure aluminum. The mouth of the pipe adopts a secondary expansion joint structure to ensure that there is no leakage outside the expansion pipe. The oil circuit of the cooler is replaced by a traditional three circuit instead of a single circuit. The oil box is formed by bending, simple structure, few leakage points, low noise, reliable operation, no leakage, high cooling efficiency and so on.