The soil-water characteristic curve (SWCC) of loess soil in Lanzhou, Gansu Province was measured by Ku-pF apparatus and pressure plate extractors, the air entry value and residual water content were suggested. The effects of dry density and wetting-drying cycle on the SWCC were analyzed through both experimental data and microstructure, and the measured SWCC was fitted with the existing models. The results show that the specimens with higher dry density generally have lower initial saturated water content, higher air entry value and better water-holding capacity. The logarithm of air entry has linear increase with the increase of dry density. The wetting-drying cycle leads to structure change and big pore increase in soil, and the water-holding capacity of loess soil can also be reduced. The SWCC of unsaturated loess soil can be descripted and predicted by the Van Genuchten model exactly.%采用Ku-pF非饱和导水仪和压力膜仪实测不同干密度和不同干湿循环状态下重塑黄土的土水特征曲线,给出黄土土水特征曲线的进气值与残余含水率等特征值,同时利用环境扫描电镜观测黄土试样的微结构特征,统计黄土孔隙结构的变化情况,从宏观和微观2方面分析干密度和干湿循环作用对黄土土水特征曲线的影响,并利用已有模型对实测曲线进行拟合.研究结果表明:干密度对黄土的土水特征曲线有显著影响;干密度大的土样具有较低的初始饱和含水率、较高的进气值和良好的持水性能,土水曲线形态平缓,土体进气值的对数随干密度增大呈线性增长规律；干湿循环作用促使土中胶结物被溶蚀,孔隙贯通或扩张,大孔隙增多,土体的持水性能降低;Van Genuchten模型可以很好地描述和预测非饱和黄土的土水特征曲线.
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