The invention relates to a method for detecting the sealability of a charging bucket rubber gasket of a blast furnace and belongs to the technical field of sealability detection. Firstly, a connection joint is opened at a blast furnace top steam pipeline, a stainless steel manual ball valve with the nominal diameter of 20mm is installed, and a seamless pipe with the nominal diameter of 20mm is laid. The seamless pipe is introduced to the charging bucket at the top of the furnace and enters into the charging bucket through an opening at the upper part of the charging bucket body. After an upper seal valve rubber gasket and a lower seal valve rubber gasket of the furnace top charging bucket are changed, an upper seal valve, a lower seal valve, an equalizing valve and a blow off valve are all arranged at a close position to ensure that the charging bucket is under enclosed state; then steam is charged into the charging bucket to be used for detecting the tightness of the upper seal valveand the lower seal valve; if the rubber ring is not sealed tightly and has the problem of air leakage, the problem is solved immediately, so as to avoid causing secondary ventilation stop of the blast furnace. The method has the advantages of playing an important role in avoiding blast furnace accidental shutdown, increasing the pig iron yield of the blast furnace and lowering the cost for maintaining and operating.