Under the background of global warming， the global water resources were projected to be a distribution of "the rich get richer， the poor get poorer". The dryness and wetness changes in arid and semi-arid areas have attracted great attention of the international community. Based on the present and future climate change scenarios， this study summarized the changes of dryness and wetness boundary and the area of arid and semi-arid areas in China characterized by 400 mm Isohyet， aridity index and Palmer drought index. The main conclusions and problems of dryness and wetness changes in recent decades and future projections were reviewed and summarized. The results show that the dry and wet boundaries and their changes in China have distinct piecewise characteristics； the middle section is relatively stable； the eastern section fluctuates violently； and the western section changes show strong data dependence. The data with more observed ones show that the western section moves steadily westward and northward. The dryness and wetness changes of different drought index analysis are not in line， especially in dry and wet transition zone. The drought index using potential evapotranspiration shows a strong dependence on temperature change. It is suggested that we should use as much observation data as possible， drought index including actual evapotranspiration， advanced land surface processes model to accurately simulate actual evapotranspiration， and high resolution dynamic downscaling results coupled with advanced land surface processes model， to study dryness and wetness changes in China.