Reduced inorganic sulfur (RIS) includes acid volatile sulfur (AVS) formed from sulfate reduction products and reactive iron (Fe_HR), elemental sulfur (S⁰), an intermediate product of sulfur, and pyrite sulfur (S_py), the ultimate accumulation material of elemental sulfur and iron in sediments. RIS can affect not only the biological effectiveness of sediment heavy metals, but also control the geochemistry of biogenic elements such as iron reduction and release of endogenous phosphorus behavior. In order to study the distribution characteristics of RIS in the sediments of the Three Gorges Reservoir area and its environmental significance, surface sediment samples were collected from 17 points in the section from Yunyang to Zigui in the Three Gorges Reservoir area in July-August and December 2017, and the RIS content was measured. The results showed that, compared with other lakes and rivers, the RIS content of surface sediments in the Three Gorges Reservoir area was lower, with AVS content ranging from 0.06 to 0.65 μmol/g, S⁰ from 0.50 to 1.66 μmol/g, and S_py from 0.96 to 17.54 μmol/g. The AVS and S⁰ contents are higher in summer than in winter, and the trend of RIS in the section from Yunyang to Zigui is roughly decreasing, then increasing and then decreasing, with obvious seasonal and regional difference. Correlation analysis, principal component analysis and cluster analysis showed that bioavailable phosphorus (BAP), Fe_HR and SO^2-₄ content in the overlying water were the main limiting factors of sediment RIS in the study area. The winter RIS in the reservoir area was significantly correlated with organic phosphorus (Org-P) and exchangeable phosphorus (Ex-P), and when the sulfide content increased, it promoted the mineralized decomposition of Org-P and the migration of Ex-P to the overlying water column, increasing the risk of phosphorus release. Meanwhile, this study assessed the waters at risk of pollution in the Three Gorges Reservoir area from the perspective of sulfur-driven eutrophication. In addition to the key tributaries in the reservoir area where typical water blooms have occurred, the Changtan River and Jiuwan River also have eutrophication problems.