The utility model discloses a novel polycrystalline silicon chamfering grinding machine. A supporting column is vertically fixed to the portion, between the two grinding wheel frames, of the workbench. A pressing cylinder is arranged at the top end of the supporting column through a horizontal connecting rod; the pressing air cylinder is connected with an air pump through an electric control valve, a first proximity switch and a second proximity switch are arranged in a strip-shaped hole in the lower portion of the side wall of the supporting column, the signal output end of the first proximity switch and the signal output end of the second proximity switch are connected with the signal input end of a controller, and the signal output end of the controller is connected with the signal input ends of the air pump and the electric control valve. The utility model has the advantages that: the utility model has the advantages that: the structure is simple; the telescopic length of the telescopic end of the pressing air cylinder is automatically controlled through the controller, the first proximity switch and the second proximity switch. Accurate control over the pressing air cylinder can be achieved, it is guaranteed that a workpiece can be stably clamped, the tool collision accident caused by looseness of the workpiece is avoided, workpiece damage caused by too large pressure dueto the fact that the telescopic end extends too long can be prevented, the personnel demand is reduced, and the labor intensity is reduced.