Hydraulic locking device

The utility model relates to a hydraulic locking device, which mainly comprises a cylinder barrel, a locking piston, a conical pressing ring, a pressing sleeve assembly, a cylinder cover, a flange cover, a disc spring and the like, wherein the pressing sleeve assembly is in conical surface contact with the conical pressing ring and the conical pressing ring is sheathed on the piston rod of a main oil cylinder. When the piston rod of the main oil cylinder moves to any position, the conical pressing ring can lock the piston rod of the main oil cylinder. When the piston rod of the main oil cylinder is required to move, pressure oil is fed into a chamber a, the disc spring is compressed, the conical pressing ring is released and the piston rod of the main oil cylinder can move freely.