Abstract: The Source Region of the Yangtze River (SRYR) serves as a crucial water conservation functional zone within the Yangtze River Basin and a vital ecological security barrier for China.Revealing the spatiotemporal variation patterns of Water Conservation Capacity (WCC) and its influencing factors in the SRYR is essential for advancing ecological conservation and restoration projects, sustaining ecological functions of the SRYR, and safeguarding river-lake health.This study applied a SWAT hydrological model to simulate hydrological processes in the SRYR and employed statistical and geostatistical methods to quantitatively identify multi-scale spatiotemporal variation characteristics and primary influencing factors of WCC in the SRYR.The results showed that: ① During 1963~2020, annual precipitation, actual evapotranspiration, runoff, and water yield in the SRYR exhibited significant increasing trends, with rates of 1.35, 1.00, 0.12 mm/a and 0.36 mm/a, respectively.Although annual WCC showed an insignificant increase trend at 0.24 mm/a, both annual and interannual variations of WCC were highly pronounced, with WCC predominantly concentrated in autumn and warm seasons.② WCC demonstrated an upstream-to-downstream increasing gradient spatially.The Tongtian River recorded the highest WCC, followed by the Dangqu River, while the Chumaer River and Tuotuo River had the lowest capacities.③ WCC was primarily governed by the comprehensive effects of precipitation, water yield, groundwater runoff, drought index, evapotranspiration potential, and land use types.The research results can provide scientific references for water resources management and ecological conservation in the Yangtze River Basin.