Hydraulic clamp

The utility model discloses a hydraulic clamp which comprises a mounting base, a supporting base is fixedly arranged above the mounting base, a rotating disc is arranged above the supporting base, and the middle of the face, corresponding to the supporting base, of the rotating disc is rotationally connected with the supporting base. A positioning structure is fixedly arranged in the middle of the upper side face of the rotating disc, and a pressing assembly is arranged on the edge of the upper side of the rotating disc, corresponds to the upper side face of the positioning structure and is movably connected with the positioning structure. A to-be-machined part is placed on the positioning structure to be positioned and preliminarily fixed, then the to-be-machined part is pressed and fixed through the pressing assembly, machining of a machining instrument is facilitated, meanwhile, the part on the positioning structure can be rotated to adjust the angle in cooperation with the rotating disc, the part does not