Abstract: Understanding the water and soil resource balance in China's critical grain-producing regions is essential for optimizing grain production structure national food . This study focuse on the Dongting Lake Basin in the southern and utilize multiple sets of land use data, conventional meteorological station data, and DEM data to systematically identify changes in cultivated land use land addition, type conversion, persistence, and loss. Additionally, the Penman-Monteith equation and the effective precipitation model employed to reveal the climate water balance characteristics and the impact of cultivated land use on water and soil resources. The results indicate : 1) Over the past 40 years, paddy fields in the Dongting Lake Basin maintained a relatively stable spatial distribution, while dryland shifted northwestward by 17.36 km2. The relative proportion of persistent cultivated land reached 70.63%, and areas with lost cultivated land primarily distributed in regions Huaihua and Xiangxi Prefecture. The newly added cultivated land s converted from forest land, conversions concentrated in areas Hengyang, Shaoyang, and Loudi; 2) The southern and Dongting Lake regions exhibit higher evapotranspiration capacity, while the western to northwestern regions lower capacity. Effective precipitation gradually increase from northwest to southeast; 3) The proportion of water-deficient areas was only 1.79% in 1980 but increased to 32.84% by 2020. The Dongting Lake region and Yongzhou face a higher risk of water deficit; 4) The climate water balance of cultivated land shifted from a surplus to a coexistence of deficit and surplus. Water-deficient areas mainly distributed in the Dongting Lake region, the northwestern part of the Xiangjiang River Basin, and Yongzhou. The expansion of water-deficient areas s mainly concentrated around changes in cultivated land use, with paddy fields as the core.Thfindings provide valuable insights for making informed decisions on the sustainable development and utilization of cultivated land in the studied basin.