The utility model discloses a cable intermediate joint waterproof explosion-proof box. The cable intermediate joint waterproof explosion-proof box comprises an upper cavity and a lower cavity which are connected through bolts. An intermediate joint cavity is formed when the upper cavity covers the lower cavity, the upper portion of the upper cavity is provided with a fast sand washing port, end heads are arranged at the two ends of the upper cavity and the lower cavity, the inner walls of the end heads are provided with a plurality of waterproof grooves, and the waterproof grooves are provided with sealing rings; and the fast sand washing port is provided with a cover body, and a flat pad for sealing is arranged between the cover body and the fast sand washing port. According to the utility model, the upper cavity and the lower cavity are provided with the waterproof grooves and the sealing rings so that the waterproof effect is good; the upper portion of the upper cavity is provided with the fast sand washing port so that fireproof anti-arc sand can conveniently fills the port; the structure is simple, and under the condition of a 1-meter water depth, water can be effectively prevented from penetrating into the explosion-proof box, such that a good operation environment is provided for an intermediate joint; and by using the cable intermediate joint waterproof explosion-proof box, the water resistance of the cable intermediate joint is improved, cable faults generated when the intermediate joint is immersed in water can be effectively inhibited, and stable operation of a power network is maintained.