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Using the precipitation from 114 stations over the Tibetan Plateau (TP) provided by the National Climate Center of the China Meteorological Administration (CMA), we found a significant wetting TP in May for the period 1979-2014, especially in the south-eastern part where the wetting trend is spatially consistent (71% in precipitation amount relative to climatology, 46% in frequency, and 33% in intensity).Circulation trends show that the enhanced precipitation over the TP is resulted from the advanced Asian summer monsoon onset (ASMO) in recent decades.Withearlier ASMOs, intensified lower-level westerly water vapor transport and convection dominate the Bay of Bengal (BOB) and south of the TP in May, favoring increased rainfall there.Meanwhile, the BOB summer monsoon onset has advanced by approximately 2 pentads since the late 1970s.The change of the BOB monsoon onset date coincides well with that of precipitation over the south-eastern TP, with a correlation coefficient of-0.73 (99% confidence level).In addition, the ecosystemsexhibitnotable changes in response to the precipitation change.The surface soil moisture in May and deep soil moisture in June also increased by 4.2% and 0.6% /decade, respectively.The Normalized Difference Vegetation Index (NDVI) in June and July has increased by 8.5%/decade with a 99% confidence level.These changes further confirm the prominent wetting trend over the TP and reveal the profound impacts of precipitation change on hydrological cycles and ecosystems.