Hydraulic locker

The utility model relates to a hydraulic locker which comprises a central pipe and is characterized in that the exterior close to one end of the central pipe is sleeved with a locking piece sleeve in a threaded manner, and the exterior of the other end is in threaded connection with an upper connector; a magnetic locking mechanism consisting of a locking piece, a magnetic cup and a magnetic block is mounted in the circumferential direction of the position where the central pipe is connected with the locking piece sleeve; and a piston connected with a sawtooth buckle of the upper connector is mounted between the central pipe located on one side of the magnetic locking mechanism and the locking piece sleeve. The hydraulic locker has the advantages that the locker can prevent risks such as shaking during large-displacement and high-sand-ratio gravel pack operation of a service pipe column, jittering and spurting of a service tool and a surface pipeline and the like, and reduce a high danger coefficient of drill