Hydraulic lifting system

The utility model relates to the technical field of a lifting system and discloses a hydraulic lifting system. The hydraulic lifting system comprises hydraulic oil output equipment, a lifting valve, a lifting oil cylinder, an unloading valve, a reversing valve and an oil tank. The hydraulic oil output equipment is connected with the lifting valve. The lifting valve is connected with the lifting oil cylinder. An oil return opening of the lifting valve is connected with an input end of the oil tank. The hydraulic oil output equipment is connected with the unloading valve. A control opening of the unloading valve is connected with an output end of the reversing valve. An oil return opening of the unloading valve is connected with an input end of the oil tank. The reversing valve is connected with the hydraulic oil output equipment. An oil return opening of the reversing valve is connected with an input end of the oil tank. When lifting is not needed, the reversing valve is in an unloading state. The through flow capacity of the unloading valve is great, so that the pressure loss of hydraulic oil is small when flowing through the unloading valve, the generated calorific value can be ignored, and thereby the hydraulic oil basically has no temperature rising. When lifting is needed, the reversing valve is in a non-unloading state, and normal lifting need is satisfied.