The methane oxidation process, driven by soil methanotrophic bacteria, plays a critical role as a sink for atmospheric methane. Accurately quantifying soil methane uptake is therefore essential for understanding global and regional methane budgets. This study enhances the soil methane uptake diffusion-reaction model(R99) by incorporating empirical data and applies the modified model to simulate methane uptake across various Chinese ecosystems from 1990 to 2020, identifying key drivers of spatiotemporal variations. The results showed that: (1) From 1990 to 2020, the average annual national soil methane uptake was approximately 2.86-3.04 Tg CH₄/a. Mean uptake rates for bare land, cropland, forest, grassland, and shrubland ecosystems were 0.53, 0.43, 0.79, 1.00, and 0.20 Tg CH₄/a, respectively, all exhibiting seasonal patterns with higher uptake in summer and lower uptake in winter. (2)Over the same period, annual soil methane uptake in southern China showed an increasing trend, while northern China experienced a decline. Overall, there was a national upward trend, with southern uptake rates exceeding those in the north. (3) Spatial differences in uptake rates were primarily influenced by temperature, precipitation, potential evapotranspiration, and soil moisture. In southern regions, rising temperatures and potential evapotranspiration were the main drivers of increased uptake, while in northern regions, reduced rainfall and soil moisture led to decreased uptake. Notably, in the Tibetan Plateau, significant increases in soil methane uptake were linked to higher soil moisture and reduced potential evapotranspiration. (4)The main factors driving uptake rates varied by ecosystem. Grasslands and bare lands were primarily influenced by soil moisture, forests and shrublands by temperature, and croplands by tillage intensity. This study provides a comprehensive assessment of soil methane uptake and its driving factors in China, offering valuable insights and methodological frameworks for national methane budget calculations.