Water shortage is a limiting factor for agricultural production in China, and climate change will affect agricultural water use. Studying the effects of climate change on crop irrigation requirement (CIR) would help to tackle climate change, from both food security and sustainable water resource use perspectives. This paper applied SDSM (Statistical DownScaling Model) to simulate future meteorological parameters in the Hetao irrigation district (HID) in the time periods 2041–2070 and 2071–2099, and used the Penman–Monteith equation to calculate reference crop evapotranspiration (ET₀), which was further used to calculate crop evapotranspiration (ET_c) and crop water requirement (CWR). CWR and predicted future precipitation were used to calculate CIR. The results show that the climate in the HID will become warmer and wetter; ET₀ would would increase by 4% to 7%; ET_c and CWR have the same trend as ET₀, but different crops have different increase rates. CIR would increase because of the coefficient of the increase of CWR and the decrease of effective precipitation. Based on the current growing area, the CIR would increase by 198 × 10⁶ to 242 × 10⁶ m³ by the year 2041–2070, and by 342 × 10⁶ to 456 × 10⁶ m³ by the years 2071–2099 respectively. Future climate change will bring greater challenges to regional agricultural water use.