Abstract: New development of mechanics and application for unsaturated soils and special soils are systematically summarized. The contents of the paper consist of developing equipment, basic property, theoretical model and application in engineering. Attention is paid to the advancing front scientific problems, such as stress theory and constitutive model of unsaturated soils, as well as the thermodynamical characteristics of buffer material. In the progress of basic property of unsaturated soils and special soils, the moisture retention, water and air migration, structural fabric evolution, strength, stress theory, constitutive model and numerical analysis are discussed in the paper in detail. Regarding research advance of special soils, 16 kinds of soils are discussed, and the loess and expansive soil widely distributed in China, as well as buffer material for geological disposal repository of high-level radioactive waste are emphatically introduced. The relative problems such as earth pressure, humidifying deformation, creep properties，immersion test, slope, dynamic property and geologic hazard are also discussed in detail. In addition, practical application of theoretical results and functional technology are introduced. Finally, some proposals for further research are presented.

Key words: unsaturated soil and special soil, engineering application, research progress