The invention relates to the technical field of watch cover machining, in particular to a grinding device for a watch cover. The grinding device comprises a fixing disc, the fixed disc is connected with a rotating shaft, and the rotating shaft is connected with a driving mechanism; a water storage tank is arranged below the rotating shaft, and the upper end surface of the water storage tank is recessed downwards and is in an arc shape matched with the edge of the watch cover; multiple cleaning wheels are rotationally arranged on the upper end surface of the water storage tank, wherein multiplebristles are arranged on half of the surfaces of the cleaning wheels, and the other half of the surfaces of the cleaning wheels are provided with multiple water outlet holes; a piston is slidably arranged at the bottom part of the water storage tank, the piston is connected with a rack, the rack is meshed with a gear, and a transmission part is connected between the gear and the rotating shaft; agrinding belt and a driving wheel are arranged above the rotating shaft, wherein a driven wheel is arranged on one side of the driving wheel, and the grinding belt sleeves the driving wheel and are refined to form an arc matched with the edge of the watch cover with the driven wheel; and an arc-shaped fixing plate is arranged on the inner side of the bottom part of the grinding belt, and multiplefixing wheels are rotationally arranged on the outer side of the bottom part of the grinding belt. According to the grinding device, the problem that the grinding efficiency of the watch cover is nothigh in the prior art is solved.