Oil-immersed power transformer is a commonly used power conversion equipment. It adopts an oil-immersed design, and the iron core and windings are immersed in insulating oil to achieve the conversion and transmission of electrical energy. Transformers are mainly composed of magnetic circuit systems, windings, cooling systems, insulation systems and control and protection systems. The magnetic circuit system can provide the conduction and conversion function of electrical energy. The windings are used to change the voltage. The cooling system cools the heat generated inside. The insulation system protects the windings and magnetic circuits. The control and protection system monitors and protects the operating status of the transformer. Oil-immersed power transformers provide stable and reliable power supply through the coordinated work of these parts.