Abstract: Soil physicochemical properties are important driving factors of carbon storage. As a key ecological barrier area in China's southwestern border region, research on the impact of soil physicochemical properties on carbon storage in the Sichuan-Yunnan ecological barrier area remains insufficient. This study couples the InVEST and OPGD-MGWR models to analyze the spatiotemporal evolution patterns of carbon storage in the Sichuan-Yunnan ecological barrier area and the driving factors of its spatial heterogeneity. The main results are as follows: From 2000 to 2020, the overall carbon storage in the Sichuan-Yunnan ecological barrier area decreased, mainly due to urban expansion and agricultural development in lowland river valleys, but local increases benefited from forest expansion and ecological projects such as returning farmland to forests. (2) NDVI, OC, and DEM are the dominant factors, with explanatory power exceeding 50%; multi-factor interactions are all enhancement types, with the strongest interaction pair being NDVI ∩ OC, revealing the role of the ecology-terrain-soil nutrient coupling mechanism. (3) The MGWR model can effectively analyze the spatial heterogeneity of different driving factors in the Sichuan-Yunnan Ecological Barrier Zone, revealing that soil physicochemical properties play a significant role in the distribution and transfer of carbon storage. By deeply analyzing the spatiotemporal changes in carbon storage and its driving mechanisms, this study provides a new framework for CS management in ecological barrier areas and similar regions. The research results are of great significance for mitigating climate issues and promoting ecological protection.