Abstract:The East Asian summer monsoon (EASM) exerts a dominant influence on the hydroclimate of eastern China. Variations in monsoon precipitation, especially extreme events, have profound impacts on societal and economic activities in the region. Understanding Holocene EASM variability is critical for deciphering its forcing mechanisms and predicting future changes. However, uncertainties in dating results, compounded by the lack of high- resolution, well- dated sedimentary records in South China, have hindered a clear understanding of Holocene hydroclimate variability in eastern China. This study presents a continuous sedimentary section (BX) from the Baxianyan karst wetland in Guilin, Guangxi. AMS14C dating and grain size analysis were conducted, revealing three distinct grain size end members (EM1- 3) with clear environmental significance, extracted using end- member model analysis (EMMA). EM1 reflects changes in wetland water level, indirectly indicating monsoon precipitation. EM3 indicates the occurrences of extreme hydrological events. Based on EMMA results, the evolution of the wetland and monsoon precipitation changes since 8. 5 ka BP were recovered. The results reveal a gradual decreasing trend in regional precipitation since the middle Holocene, showing three stages: ① From 8. 5 to 6. 35 ka BP, higher precipitation prevailed, leading to the formation of a shallow lake in Baxianyan; ② between 6. 35 and 4. 15 ka BP, Baxianyan transitioned into a swamp under a progressively drying climate, with three extreme hydrological events identified at 6. 25~6 ka BP, 5. 2~4. 9 ka BP, and ~4. 5 ka BP; ③ from 4. 15 to 0. 15 ka BP, water levels continued to decline, with a brief rise occurring between 1. 3 and 0. 7 ka BP. Comparison with regional records indicates that the monsoon precipitation history recorded in the Baxianyan sedimentary sequence is consistent with the East Asia summer monsoon intensity. Periodicity analysis of EM1 suggests that solar activity has been the main driver of monsoon precipitation changes since the middle Holocene. In addition, atmosphere- ocean interactions in low- altitude regions (such as ENSO) have also exerted significant influence on monsoon precipitation in South China.