The utility model discloses a PCB grinding machine. The PCB grinding machine comprises a work table, a first guide rail, two second guide rails, a third guide rail, a grinding assembly and a servo system. The two second guide rails are arranged on the two sides of the work table in parallel, the first guide rail is arranged on the two second guide rails in a crossing mode and can move along the second guide rails, and the third guide rail is vertically arranged on the first guide rail and can move along the first guide rail. The grinding assembly is arranged on the third guide rail and can vertically move along the third guide rail. The servo system is used for controlling the first guide rail, the third guide rail and the grinding assembly. The PCB grinding machine is simple in structure and convenient to operate. The servo system controls the third guide rail to move on the first guide rail and the first guide rail to move on the second guide rails so as to achieve flexible adjustment of the grinding position of a PCB, and controls the grinding assembly to vertically move on the third guide rail so as to achieve adjustment of the grinding amount, and therefore the different height portions of the PCB can be appropriately ground, and the phenomenon that a base material of the PCB is exposed or resin is not ground off completely can be avoided.