Jack

The utility model relates to the technical field of jacks, and discloses a jack which comprises a fixing sleeve, a stud, a nut and a set screw, and the fixing sleeve is provided with a vertical containing hole; the bottom end of the stud is arranged in the containing hole in a sliding mode, the top end of the stud is used for supporting a workpiece, a locking groove is formed in the side wall of the stud in the length direction of the stud, and the depth of the locking groove is gradually increased in the direction from the top end to the bottom end of the stud; the nut is in threaded connection with the stud and abuts against the top end of the fixing sleeve, and the stud can slide up and down along the fixing sleeve by rotating the nut; the fastening screw is in threaded connection withthe side wall of the fixing sleeve, and the top end of the fastening screw can extend into the locking groove and abut against the bottom of the locking groove so as to fasten the stud. The bottom ofthe locking groove is obli