The invention relates to an ocean platform hydraulic oil pumping unit which comprises a combined hydraulic cylinder, an upper rack, a lower rack, a movable belt wheel assembly, an avoidance locking device, a belt, a rope hanger, a hydraulic station, an electric control cabinet, an energy accumulator and a fixed belt wheel assembly, wherein the fixed belt wheel assembly is mounted on the top of the upper rack; a belt wheel bypasses one end of the movable belt wheel assembly and one end of the fixed belt wheel assembly to be connected with the rope hanger; the other end of the movable belt wheel assembly and the other end of the fixed belt wheel assembly are fixedly arranged on the lower rack to form a lifting system; the combined hydraulic system is fixed on the lower rack; a piston rod is connected with the movable belt wheel assembly; the electric control cabinet and the energy accumulator are mounted on the lower rack; a rail wheel is fixedly arranged on the bottom of the lower rack; the avoidance locking device is connected with the rail wheel and a rail; the hydraulic station is connected with the combined hydraulic cylinder and the energy accumulator to realize the balance of the oil pumping unit; the electric control cabinet is connected with the hydraulic station; and the hydraulic system is controlled by an electrical control system to realize on-off reversing of the oil pumping unit. The ocean platform hydraulic oil pumping unit has the beneficial effects that the structure is simple and compact, long-stroke and low-jig frequency requirements can be realized, and an electric submersible pump is replaced to realize sucker-rod oil extraction on the sea.