Under global climate change, the hydrological cycle intensifies and the wetting and drying over land is decoupled with atmospheric drying and vegetation greening. This triggers a hot debate on the changes in dryland area. To clarify that, we summarized trends of some widely-used aridity indicators, as well as their driving factors. We then classified these indicators into different groups based on their trends to explore the underlying mechanism of the coupled and decoupled trends among indicators. At last we provided prospect of future research on wetting and drying under climate change. Our results showed that among aridity indicators, vapor pressure deficit, aridity index, and soil moisture presented significant drying trends, vegetation greenness and productivity showed obvious wetting trends, while precipitation, runoff, terrestrial water storage and other composite indices showed great regional discrepancy but overall insignificant trends. Increasing CO₂ concentration, higher temperature, and human direct activities such as land use/cover change are the major factors causing differentiation among trends of the indicators, which accounts for the contradiction in dryland change (expanding or shrinking) in studies using various indicators. Therefore, a comprehensive assessment of changes in wetting and drying for terrestrial land is essential in the future by focusing on four priorities:1) multiple dimensions assessment including meteorology, ecology and hydrology; 2) interactive relationships (such as promotion, limitation and regulation) among multi-dimensional elements and their impact on wetting-drying changes under the double natural and human pressures; 3) the occurrence of extreme events (such as drought, flood, and heat wave) and the areas (such as semi-arid regions) sensitive to climate change in the process of wetting-drying; and 4) the possible solution to global climate change based on vulnerability assessment and adaptive governance.