The utility model discloses a barrel oil box of oil-immersed reactor which comprises a box cover, a box wall, a box bottom and a box edge, wherein the box cover and the box bottom are both flat type, the box wall is divided into four planes, each plane is provided with grooved reinforced iron, the grooved reinforced iron is filled with sand, the box wall is welded with the box edge and the box bottom, and the box edge is located on the top of the oil box. The appearance of the barrel oil box of oil-immersed reactor is concise and aesthetic, the horizontal reinforced iron of the oil box is reduced, and the welding wires of the oil box are reduced, which not only prevents oil leakage, but also reduces workload of operators, and saves labor cost, the smooth box wall can increase the placing area of the grooved reinforced iron filled with sand, and the barrel oil box of oil-immersed reactor not only can strength the mechanical intensity of the oil box, but also plays the role of damping vibration, and improves production efficiency.