The invention discloses a hydraulic steering system which comprises a steering pump and an overflow valve. The steering pump supplies oil to a steering oil cylinder through an oil supply path, and overflowing can be achieved through the overflow valve. A first reverse valve controlling the overflow valve to be opened and closed is further arranged. The hydraulic steering system can control the overflow valve to be closed and opened. Therefore, the overflow valve can be closed in the steering process, the overflow valve is opened in the non-steering process to achieve overflowing, and overflow pressure does not correlate to steering oil path pressure any more. Therefore, the overflow pressure of the overflow valve does not need to be as high as that in the prior art so that pressure needs of steering can be met. Therefore, according to the scheme, overflow losses in the non-steering process are small, and energy consumption is lowered.