The invention discloses an oil-immersed transformer. The oil-immersed transformer provided by the invention comprises an oil tank, wherein the oil tank is used for holding transformer oil; a transformer core and coils which are set in the oil tank; an oil conservator which is configured above the oil tank; and heat dissipaters which are configured at the sides of the oil tank. The oil tank is at least partially made of an insulation material. Outgoing line terminals of the oils are set at the position of the insulation material. According to the oil-immersed transformer, the oil tank is at least partially made of the insulation material and the outgoing line terminals of the oils are set at the position of the insulation material, so the problem that an insulation bushing is high in faultrate can be solved well.