The invention discloses an oil-immersed transformer which comprises a tank body and a base, wherein a transformer body is mounted inside the tank body; the outer side of the transformer body is filledwith heat radiation oil; the base is arranged below the tank body; support legs are symmetrically arranged at the lower end of the tank body; and the lower ends of the support legs are sleeved by support sleeves in a sliding manner. The oil-immersed transformer is simple and reasonable in structure and high in anti-seismic property, the temperature of an oil liquid inside the tank body can be detected through a temperature sensor, furthermore the temperature can be divided into three temperature values, when the temperature is a first temperature value, the result shows that heat radiation requirements can be met by passive heat radiation, then primary heat radiation and secondary heat radiation do not act up, when the temperature is a second temperature value, the primary heat radiationworks independently, when the temperature is a third temperature value, the primary heat radiation and the secondary heat radiation are informed to work, then gradient heat radiation can be achieved,energy conservation can be assisted, heat radiation can be carried out through cooling water and water vapor heat absorption when heat of the device is radiated, and compared with conventional air cooling, the heat radiation mode is relatively good in heat radiation effect and high in practicability.