Southeast Asia,characterized by intricate topography and dense population,is highly sensitive to precipitation extremes in the context of global warming,making understanding its future change characteristics essential.This study utilizes 26 global climate models (GCMs) to project changes in precipitation extremes over Southeast Asia by the end of the 21st century,based on the Shared Socioeconomic Pathway (SSP) scenarios 2-4.5 and 5-8.5 (SSP2-4.5 and SSP5-8.5) simulations from the Coupled Model Intercomparison Project phase 6 (CMIP6).By decomposing the moisture budget equation,we quantify the relative contributions of increased atmospheric specific humidity and alterations in atmospheric circulation to climatological precipitation changes.The research explores both dynamic and thermodynamic mechanisms driving these precipitation changes,rigorously evaluating the consistency and reliability of simulation outputs across a diverse range of climate models.The multi-model ensemble medians (MMM) reveal that,compared with the historical reference period (1985—2014),climatological precipitation and precipitation extremes in most of Southeast Asia will increase significantly by the end of the 21st century (2071—2100) under SSP2-4.5 and SSP5-8.5 scenarios.Precipitation extremes exhibit spatial differences,with short duration,high intensity events predicted for Kalimantan,while southern Sumatra experiences a decrease in total precipitation on wet days (PRCPTOT) and an increase in consecutive dry days (CDD).Except for heavy precipitation days (R10mm),extreme precipitation indices show more pronounced magnitudes under the SSP5-8.5 scenario than the SSP2-4.5 scenario.The contribution rate of heavy precipitation (R95pTOT) increases by 22％ (41％) under SSP2-4.5 (SSP5-8.5) scenario.Climatological precipitation at the end of this century exhibits an obvious increasing trend across most regions of Southeast Asia under SSP2-4.5 and SSP5-8.5 scenarios,with large increases mainly observed in Kalimantan and New Guinea Island.Spatial patterns of precipitation alterations align closely with changes in P-E (precipitation minus evaporation),with the magnitude of evaporation change being modest.This suggests that the enhancement in climatological precipitation is the dominant factor contributing to the increase in P-E.Quantitative analysis of the moisture budget equation indicates that thermodynamic and dynamic effects mainly result in climatological precipitation changes by the end of the 21st century.The thermodynamic component,with higher inter-model consistency,contributes the most,accounting for 65％ (64％) of the P-E changes under SSP2-4.5 (SSP5-8.5) scenarios.However,dynamic effects counteract the changes in P-E,contributing 35％ (36％).Moisture convergence caused by atmospheric-specific humidity changes is considered the dominant factor in the projected precipitation increase.This conclusion underscores the need for a thorough assessment of the risks associated with extreme climatic conditions in Southeast Asia and emphasizes the importance of proactive measures to mitigate the risks posed by precipitation extremes in the region.