Abstract: Crop water requirement is the baseline in estimating the water-saving potential of irrigation districts. With this baseline, a series of factors, such as effective precipitation, groundwater, water use efficiency (WUE) in the irrigation ditch, WUE in the cultivation field and structure of crop cultivation, were taken into account. A method to estimate water-saving potential in irrigation districts was developed in this paper. The water-saving potential in the Hetao Irrigation District was accordingly estimated by this proposed method. The results show that the Hetao Irrigation District has a water-saving potential of 2 billion m³ if current irrigation areas meet the present water-saving standards, which is possible in the next 25～30 years.