Chuck for fixing sleeve in underwater blasting

The utility model discloses a chuck for fixing a sleeve in underwater blasting, which comprises a sliding seat, a chuck body, a clamp block, an oil cylinder and a valve, the chuck body is provided with a U-shaped bayonet for placing the sleeve, the open end of the U-shaped bayonet is provided with the valve, and the valve is detachably connected with the chuck body; the clamp blocks and the oil cylinders are arranged on the two sides of the U-shaped bayonet respectively, the number of the clamp blocks is at least four, and the clamp blocks are driven by the oil cylinders so as to clamp and loosen a casing pipe. The sliding seat is arranged on the back face of the chuck body, namely the sliding seat is far away from the opening end of the U-shaped bayonet. According to the utility model, the four clamp blocks are uniformly arranged in the chuck body, so that the sleeve is uniformly stressed in the working process of clamping the sleeve, the sleeve is not easy to deviate due to impact of other factors such as w