The utility model relates to a vehicle transmission system for height reduction of a whole vehicle. The vehicle transmission system comprises a front driving axle (5), a back driving axle (6), an engine (1), a hydraulic gearbox (2), and corresponding transmission shafts (4), wherein the engine (1) is positioned between the front driving axle and the back driving axle. The vehicle transmission system is characterized in that the engine (1) and the hydraulic gearbox (2) are arranged in a parallel-axis way, and are connected by a middle transmission device (3), and the middle transmission device (3) is transversely arranged between the output end of the engine (1) and one side of the input end of the hydraulic gearbox (2). The vehicle transmission system has the advantages that the longitudinal and transverse sizes of the engine and the gearbox are adjusted, so the height of the whole vehicle is strictly controlled; the hydraulic gearbox is arranged near the geometric center line of a main vehicle frame, and the hydraulic gearbox respectively outputs power to the front driving axle and the back driving axle through the transmission shafts; and the layout is compact, and the height of the whole vehicle is controlled.