Abstract: Improving soil organic carbon is crucial for combating climate change and enhancing soil fertility. This study uses survey data on the physicochemical properties of the topsoil (0-30 cm) from 14 501 measurement points in tobacco fields across Yunnan Province, collected in 2018. The study calculates the organic carbon content, carbon density, and carbon sink storage in the topsoil of each county, tobacco-growing region, and the entire province, while analyzing their spatial distribution. Pearson correlation and curve regression analysis were used to identify the key factors influencing soil organic carbon levels in tobacco fields. The findings reveal that the average organic carbon content in the tillage layer of tobacco fields is 17.15g/kg, with a carbon density of 60.50t/hm2 and a total carbon sink of 2,397.80 million tons. The ranking of soil organic carbon content in the tillage layer across different tobacco-growing regions is as follows: East Yunnan > West Yunnan > Southeast Yunnan > Northeast Yunnan > Central Yunnan > Southwest Yunnan. In terms of carbon density, the order is: East Yunnan > West Yunnan > Central Yunnan > Southeast Yunnan > Northeast Yunnan > Southwest Yunnan. For soil carbon sink capacity, the ranking is: West Yunnan > East Yunnan > Central Yunnan > Southeast Yunnan > Southwest Yunnan > Northeast Yunnan. Soil organic carbon content in the topsoil of tobacco fields is strongly positively correlated with soil alkali-hydrolyzable nitrogen, available phosphorus, available potassium, and average annual precipitation (p < 0.01). It is negatively correlated with average annual temperature, sunshine hours (p < 0.01), and soil pH (p < 0.05). Of these factors, alkali-hydrolyzable nitrogen content is the primary explanatory factor for the spatial variation of soil organic carbon content. This study provides a detailed and systematic assessment of soil organic carbon in tobacco fields at the regional level in Yunnan Province. Its findings offer valuable insights for the tobacco industry for improving soil fertility and productivity.