简要分析了西北黄土梯地和四川紫色土旱坡地土壤水侧向运移的特点，介绍了地下地膜截水墙阻断土壤水分侧向运移、保持耕地土壤水分、抗旱增产的基本原理和建设技术。陕北米脂黄土梯田的试验结果表明，该技术可以有效地减少梯田梯坎蒸发，增产效益显著（５７７％～８８６％）。该技术也非常合适解决四川丘陵区紫色土旱地季节性干旱问题，可以减缓干旱的发生和减轻干旱造成的损失 This paper briefly analyzes the characteristics of lateral movement of soil water in Northwest Loess Ladder and Slope Land of purple soil in Sichuan Province, introduces the basic principles and construction of underground plastic membrane cutoff wall to block the lateral migration of soil moisture, maintain the soil moisture and increase drought resistance technology. The test results of the rice-fat loess terraced fields in northern Shaanxi show that the technology can effectively reduce the evaporation of the terraced fields, yielding significant benefits (577% ~ 886%). This technique is also very suitable to solve the seasonal drought in purple soil dryland in Sichuan hilly area, which can reduce the occurrence of drought and alleviate the loss caused by drought