The invention relates to a polishing device, in particular to a water drill bit polishing device. According to the water drill bit polishing device, a water drill bit can be automatically fixed, and is polished, and the water drill bit can be automatically replaced. The water drill bit polishing device comprises a polishing base, a polishing mechanism is arranged between the front left side and the right side of the polishing base, a clamping mechanism is arranged between the rear side and the front side of the polishing base, the clamping mechanism is connected with the polishing mechanism, through the polishing mechanism, automatic polishing of the water drill bit can be achieved, after the water drill bit is polished, the polishing head can automatically move upwards to be separated from the water drill bit, through the clamping mechanism, during polishing, the water drill bit is clamped and rotates, after polishing, the clamping mechanism can automatically loosen the water drill bit, through a placing mechanism, manual taking and replacing of the water drill bit can be facilitated, and through an automatic conveying mechanism, automatic replacing of the water drill bit can be achieved.