Hydraulic joint of multi-degree-of-freedom mechanical arm

The utility model relates to a hydraulic joint of a multi-degree-of-freedom mechanical arm. The hydraulic joint comprises a base and a top plate, three or more hydraulic rods are arranged on the base at intervals in the circumferential direction, guide grooves with the number equal to that of the hydraulic rods are formed in the top plate at intervals in the circumferential direction, and the length direction of each guide groove points to the central axis of the top plate from outside to inside in the radial direction. A sliding block is movably installed in each guide groove in the length direction of the guide groove in a guiding mode, each sliding block is provided with a hemispherical installation groove facing the base, the movable end of each hydraulic rod is provided with a ball head end, and each ball head end is correspondingly nested in the corresponding hemispherical installation groove and can freely rotate. The inclination angle of the top plate is controlled by controlling the stroke of each hy