Abstract: Three problems in the current researches on soil-water retention characteristics are analyzed and discussed, and the following main conclusions are drawn. The soil-water retention characteristics are one of the constitutive relations of unsaturated soils, and they cannot replace other constitutive relations. Exploring the soil-water retention properties with perspectives, theories and methods for studying the constitutive relations can improve the research level. The forms of the soil-water characteristic curve of soils with different types and in different regions are very different, and it is difficult to describe them with the same empirical equation in the existing literatures. The testing method is an effective and reliable way to determine the soil-water characteristic curve. The time required to measure the soil-water retention characteristic curve can be dramatically shortened by improving the suction-measuring technology and the testing method. The actual suction magnitude of filling soil, loess, expansive soil, red clay, etc., which are often encountered in projects, does not exceed 1500 kPa in their working environment. The reasonable suction range, which has a significant effect on deformation and strength of soils, is narrower. So there is no need to spend a long time to obtain the complete soil-water retention characteristic curve for the full suction range.