Abstract: In the past 100 years,a global warming with regional difference occurred,which induced the dry regions became drier and wet regions became wetter.As one of the major arid regions in the world,the drying and wetting changes over the arid regions in Central Asia played an important role in ecosystems in these regions.The global monthly Palmer Drought Severity Index (PDSI) was applied to explore the spatiotemporal characteristics of the drying and wetting trends over the arid regions in Central Asia during the period of 1950-2014. The results showed that a weak wetting trend was obtained in these regions,and such trend became more significant after the 1980s.A nonlinear trend with a 3-7 year period was found according to the ensemble empirical mode decomposition (EEMD) method,which was consistent with the multi-periodic precipitation variation in Central Asia.A drying trend occurred in the five countries in Central Asia but a wetting trend in northwest China,which was consistent with the variation trend of precipitation over these regions.In addition,the results revealed that it was not true that the “dry regions become drier,and the wet regions become wetter” in Central Asia. These findings provide the important scientific bases for the water sources utilization and the sustainable development of ecosystem.

Key words: drying or wetting trend, PDSI, spatiotemporal pattern, Arid Region of Central Asia