The invention discloses a synchronous hydraulic cylinder comprising a cylinder body, a valve core and end covers at the two ends of the cylinder body. A passage is transversely formed in the cylinderbody, and the valve core can be horizontally and slidably assembled in the passage. The valve core is internally provided with two cavities partitioned by a partition plate, and a plurality of liquidoutlets are radially formed in the periphery of the cylinder body. The valve core is overall of a hollow three-section-shaft structure, and two sets of flow passes are radially formed in the peripheryof a middle shaft section. The peripheries of a left shaft section and a right shaft section are sleeved with piston rings correspondingly, the two ends of the passage are partitioned into pre-pressing cavities and pressure releasing cavities through the end covers, the piston rings and the valve core, the two ends of the valve core protrude out of the passage, and liquid injecting holes are radially formed in the two ends of the valve core correspondingly. Two sets of pressure release oil ways are formed in the middle shaft section, liquid outlet oil ways are radially formed in the peripheryof the cylinder body and are each connected with a pressure releasing oil tank, and pre-pressing oil pipes are arranged on the end covers in a penetrating mode. According to the technical scheme of the synchronous hydraulic cylinder, the function that the synchronous hydraulic cylinder has diversified work states can be effectively achieved, the function that a plurality of devices synchronouslyconduct multiple work procedures is achieved, the work efficiency is greatly improved, the structure is concise, and use is reliable.