Based on daily surface sensible heat flux（SH）data from 73 meteorological stations across the centraleastern Qinghai-Xizang Plateau，daily precipitation data from 402 stations in southern China，and ERA5 reanalysis data，this study investigates the springtime enhancement characteristics of SH over the central-eastern Qinghai-Xizang Plateau，its influence on spring rainfall in southern China，and the associated physical mechanisms. The results indicate that：（1）The springtime surface sensible heat peak time（T）and enhancement intensity（Q） over the central-eastern Qinghai-Xizang Plateau exhibit significant interannual and decadal variability，with a strong positive correlation between them. Specifically，a later occurrence of the peak sensible heat in spring is as‐ sociated with a stronger enhancement intensity.（2）Both T and Q exhibit significant positive correlations with spring rainfall in southern China. To evaluate their combined effects，a composite index termed the Surface Sensible Heat Enhancement Index（ISH）is introduced. This index demonstrates a strong positive correlation with spring rainfall in southern China（correlation coefficient = 0. 60，p<0. 01）. Moreover，its influence is largely in‐ dependent of external factors，such as sea surface temperatures in the central-eastern Pacific and the tropical Indi‐ an Ocean.（3）In years with a high（low）ISH index，the springtime subtropical westerly jet is anomalously south‐ ward（stronger），and the westerly winds south of the Qinghai-Xizang Plateau are anomalously strong（weak）. The average geopotential height at 500 hPa and 850 hPa over the Chinese mainland is anomalously lower（high‐ er），and the lower troposphere in southern regions is dominated by an anomalously low（high）pressure system. In eastern coastal areas，the low-altitude southwest（northeast）wind is anomalously stronger，leading to water vapor convergence（divergence）. Combined with warm（cold）advection and strong ascending（descending）mo‐ tion，this creates conditions that are conducive（not conducive）to precipitation formation. Consequently，spring rainfall in southern China becomes anomalously abundant（scarce）. This study provides new insights into the fac‐ tors contributing to spring rainfall variability in southern China，improves the predictability of regional spring weather and climate，and provides a robust scientific foundation for mitigating disaster risks associated with ab‐ normal spring rainfall patterns.