The invention relates to a blowout prevention box for a pumping steel wire rope, which comprises a safety pull-out mechanism and a seal mechanism arranged on the safety pull-out mechanism, wherein the seal mechanism consists of a primary sealing element and a secondary sealing element which are arranged from bottom to top; a backflow chamber is formed between the primary sealing element and the secondary sealing element, and a diversion pipe is arranged on one side of the backflow chamber; the primary sealing element and the secondary sealing element are formed by an air cylinder and a sealing strip which is arranged in the air cylinder and extends along the axial direction of the air cylinder; a through hole through which the steel wire rope passes is formed in the center of the air cylinder, and the sealing strip is arranged on the periphery of the through hole; and the steel wire rope passes through the backflow chamber. The blowout prevention box has the advantages of solving the problem of the sealing of the steel wire rope effectively by the primary sealing element, the secondary sealing element and upper and lower centralizers, along with energy conservation and environment friendliness.