The utility model discloses a waterproof sleeve for a cable of an underground substation. The water proof sleeve comprises a first pipe segment used for being embedded in a lining of the underground substation and a second pipe segment used for being embedded in an underground continuous wall, the first pipe segment and the second pipe segment are coaxially arranged, an end for the butt joint of the first pipe segment and the second pipe segment is arranged as an expansion end, and the second pipe segment is bonded into the expansion end in an insertion manner via waterproof bonding agents. The waterproof sleeve for the cable of the underground substation is applicable to secondary construction processes of the underground continuous wall and the lining of the underground substation, defects in the prior art are overcome, the problem of the embedding of the waterproof sleeve in the secondary construction of the underground continuous wall and the lining can be conveniently solved, the problem that eddy current is generated when a single-core cable passes through the waterproof sleeve made of magnetic conductive materials such as steel pipes is also solved, and compared with a metal waterproof sleeve, the cost of the water proof sleeve is greatly reduced.