The invention discloses a novel partial-discharge-free oil guide box structure. The novel partial-discharge-free oil guide box structure comprises an oil guide box, a hand hole flange welded to the upper surface inside the oil guide box and an oil box covering plate in threaded connection with the hand hole flange through a hexagon socket countersunk head screw, a slope is formed between the upper surface and the lateral side of the oil guide box through two 135-degree bent structures, and first hand hole openings are formed in the slope at intervals in the direction of the horizontal middle line of the slope. Second hand hole openings corresponding to the first hand hole openings are formed in the inner side of the hand hole flange, second thread holes are formed in the periphery of the face, in contact with the oil guide box, of the hand hole flange, and a neck is formed in the edge of the outer side of the face, in contact with the oil guide box, of the hand hole flange. First thread holes corresponding to the second thread holes are formed in the periphery of the surface of the oil box covering plate. According to the novel partial-discharge-free oil guide box structure, when an induced voltage test is carried out on an extra-high voltage transformer, the medium-voltage partial-discharge amount can be controlled to range from 20 pC to 30 pC and is basically a background partial-discharge amount, and safe running of the transformer can be guaranteed.