The utility model provides a reforming reactor capable of reducing catalyst leakage. The reforming reactor capable of reducing catalyst leakage mainly comprises an oil gas inlet/outlet, catalyst diplegs, a cover plate, sealing sleeves, an oil gas distributor, a catalyst bed layer and a central tube, and is characterized in that the catalyst diplegs are inserted in the lower part of the cover plate, sealing backing rings are sleeved on the catalyst diplegs, the sealing sleeves are sleeved at the upper part of the catalyst diplegs, the sealing backing rings are clung to the upper surface of the cover plate, and the sealing sleeves are pressed at the upper parts of the sealing backing rings, so that good sealing is formed between the catalyst diplegs and the cover plate. The reforming reactor capable of reducing catalyst leakage has the advantages that the sealing backing rings which are additionally arranged between the sealing sleeves on the catalyst diplegs and the conical cover plate can be used for effectively reducing the leakage of a catalyst at leakage parts between the sealing sleeves and the conical cover plate and even eliminating the leakage, so that the machining cost is reduced, and the safe, stable and long-periodic operation of the device can be ensured.