The utility model discloses an oil tank for oil -immersed transformer, including the tank wall, the tank wall is welded by the second bounding wall that the first bounding wall of right angle shape and right angle appeared to form in opposite directions, first bounding wall corresponding to the antetheca and the you bi of tank wall, the second bounding wall corresponding to the zuo bi and the houbi of tank wall, the zuo bi of tank wall and the through -hole that right each division of wall has a rectangle, the outside of tank wall is equipped with the cover and is in buckled plate on the through -hole, the width ratio of buckled plate the big 30mm of width of through -hole, the high highly big 30mm than the through -hole of buckled plate, the buckled plate is buckled by the steel sheet that 1.2mm is thick and is formed, be equipped with on the buckled plate with the through -hole vertically, along the width direction parallel arrangement's of through -hole ripple, the upper and lower both ends of buckled plate be equipped with with the width direction of through -hole is parallel, connects each corrugated round steel on the buckled plate. Its technological effect is: the leakproofness is good, and the size is little, and the preparation is convenient, and the appearance symmetry is pleasing to the eye.