The invention discloses a hydraulic system of a highway-railway dual-purpose snow sweeper. The hydraulic system comprises a lifting hydraulic cylinder, a rotary motor, a hoisting hydraulic cylinder, a travelling motor, a hydraulic driving motor, steering hydraulic cylinders, a hydraulic pump set, four three-position six-way hydraulic directional valves and three two-position three-way directional valves, and further comprises a lifting operation valve, a rotary operation valve and a hoisting operation valve. The lifting hydraulic cylinder, the rotary motor, the hoisting hydraulic cylinder and the travelling motor are each connected to the hydraulic pump set through one three-position six-way hydraulic directional valve; a pressure relief valve is arranged on a main loop of the hydraulic pump set in a matched mode; the hydraulic driving motor is connected with the hydraulic pump set through the two-position three-way directional valves; and a direction machine is used for controlling oil inlet and oil outlet of the two steering hydraulic cylinders. The mode of pure hydraulic drive is adopted, only an engine needs to drive the hydraulic pump set to work, snow removing operation can be achieved through the lifting operation valve, the rotary operation valve and the hoisting operation valve, and the stability of the system is guaranteed.