The utility model discloses a hydraulic driving system, which is applied to an engine and comprises a plurality of pumps, a plurality of motors and a hydraulic oil tank, wherein the pumps are connected with a force taking opening of the engine, each motor is connected with one corresponding pump, an oil inlet of the hydraulic oil tank is respectively connected with the plurality of motors, an outlet of the hydraulic oil tank is respectively connected with the plurality of pumps, the number of the pumps is identical to the number of the motors, and in addition, the force taking opening is a single force taking opening of the engine, so that the plurality of pumps are connected with the engine through one force taking opening. The hydraulic driving system has the advantages that the pumps and the motors, which are sequentially connected with the hydraulic driving system are correspondingly driven only through one force taking opening of the engine, and the defect that the overall arrangement cannot be realized when more systems need to take force through the engine since the number of the force taking opening of the engine is limited in the prior art is overcome.