Objective  This study aimed to explore the water requirement characteristics and influencing factors of main crop growth in the Yanqi Basin of Xinjiang, in order to provide reference for efficient utilization of agricultural water resources and optimization of crop planting structure in arid areas.

  Methods  Daily meteorological data from three meteorological stations in the Yanqi Basin between 2000 and 2020 were analyzed using the Penman-Monteith formula and the crop coefficient method to calculate the water requirement, effective precipitation, and irrigation water requirement of the main crops during their growth period. The Mann-Kendall test was used to quantitatively study the distribution characteristics, changing trends, and influencing factors of the above data by using the linear analysis method and path analysis method.

  Results  ① The evapotranspiration of reference crops has been increasing year by year in the past 21 years, with a change rate of 6.90 mm a⁻¹, a distribution range of 960.20 to 1264.50 mm, and an annual average of 1154.70 mm. ② The water requirement of main crops during the whole growth period ranged from 374.94 to 713.37 mm, and the peak values of crop water requirement, effective precipitation, and irrigation water requirement in different growth stages all occurred in the middle growth stage, which ranges from 247.32 to 497.92 mm, 7.14 to 21.94 mm, and 240.18 to 475.99 mm, respectively, all of which are higher than the other growth periods. ③ The water requirement and irrigation water requirement of main crops showed an increasing trend, with an average change rate of 3.86 mm a⁻¹ and 4.09 mm a⁻¹, respectively. While effective precipitation showed a decreasing trend, with an average change rate of −0.23 mm a⁻¹. ④ The primary factors for the water requirement of main crops included average wind speed, average temperature, maximum temperature, and sunlight duration. The leading factors for the irrigation water requirement of main crops were average wind speed, sunlight duration, maximum temperature, and precipitation.

  Conclusion  The distribution of effective precipitation during each growth stage of main crops is uneven. Even the effective precipitation reaches its peak in the middle growth stage, agricultural irrigation is still necessary to meet the water requirement for crop growth. Therefore, improving the irrigation system is crucial to improving the efficiency of agricultural water use, ensuring grain output, and promoting sustainable development of agriculture in arid areas.