The utility model discloses a middle scarifier for a grader. The middle scarifier is a soil scarifying device mounted between a steering front axle and a working scraper knife of the grader and consists of teeth, a base, a connection plate, plugs, a pin shaft and a hydraulic system, wherein the teeth are locked in rectangular through holes of the base by the plugs; the base is connected with a front frame of the grader by the connection plate; and one end of a hydraulic cylinder of the hydraulic system is connected with a front frame spherical hinge of the grader, while the other end of the hydraulic cylinder is connected with a base spherically hinge. The height above the ground and the depth into the soil of the scarifier are changed by controlling the telescoping of the hydraulic cylinder.