The invention discloses an oil-immersed power 
transformer which structurally comprises an 
oil tank, a heat dissipation device, corrugated cooling fins, a high-
voltage terminal, a low-
voltage terminal,an oil 
pipe, an oil conservator and a supporting frame, the top of the 
oil tank is mechanically connected with the supporting frame, the oil conservator is installed on the supporting frame, and theoil conservator is communicated with the 
oil tank through the oil 
pipe. Compared with the prior art, the power 
transformer has the beneficial effects that the heat dissipation 
pipe communicated with the oil tank is additionally arranged outside the oil tank, direct contact between oil and the heat dissipation pipe is achieved, heat dissipation of the oil is facilitated, the U-shaped cooling fins of different specifications are arranged outside the heat dissipation pipe body to be wavy, air circulation is facilitated, the heat dissipation efficiency can be further improved, a 
piston block, a measuring tape, a corrugated pipe and other components are additionally arranged in the heat dissipation pipe, 
oil can be pushed into the oil tank to reduce oil heat, rapid heat dissipation of 
transformer oil can be achieved, the 
piston block can prevent 
transformer oil residues from adhering to the interior of the heat dissipation pipe while pushing the oil, and therefore it can be avoided that a channel in the inner wall of the heat dissipation pipe becomes small, oil flux is reduced, and oil heat dissipation is affected.