Abstract: Abstract: Background Existing studies on soil and water conservation carbon sequestration mainly focus on small watershed projects and regional carbon sink assessment, while specialized evaluation systems and unified technical standards for carbon sequestration accounting of production and construction projects are still lacking at the national level. Inconsistencies in baseline setting, accounting parameter selection and field monitoring methods lead to large numerical deviations and poor comparability of carbon sequestration results, which restrict macroscopic carbon aggregation and carbon trading applications. Against the deficiencies in carbon sequestration evaluation for large-scale production and construction projects, this study aims to quantify the carbon sink contributions of soil and water conservation measures in dry-hot valley regions and support the standardized monitoring and quantitative evaluation of soil and water conservation carbon sequestration for engineering projects. Methods Taking the Suwalong Hydropower Station located in the upper reaches of the Jinsha River as the research object, this study defined the scenario without any soil and water conservation measures after project approval as the accounting baseline and adopted the officially approved soil and water conservation prevention and control scope as the research boundary. A comprehensive carbon sequestration evaluation system integrating vegetation carbon enhancement, soil conservation carbon sequestration, and erosion-induced carbon emission reduction was established. Based on field plot investigation, systematic data collection and numerical model calculation, the carbon sequestration effects of different soil and water conservation measures were quantitatively analyzed, and the dominant influencing factors and optimal improvement pathways of carbon sink capacity for large hydropower projects in dry-hot valley areas were clarified. Results The results show that: 1) The total carbon sequestration of soil and water conservation measures of the Suwalong Hydropower Station reached 4883.52 t C, equivalent to 17906.24 t CO₂, with an average annual carbon sequestration intensity of 7.81 t CO₂/(hm2·a), demonstrating prominent ecological benefits of carbon sequestration and emission reduction. 2) In terms of functional zoning, the construction and production living area was the core carbon sink region, with the highest carbon fixation rate and total carbon sequestration of 1842.89 t C and an annual unit-area carbon sequestration of 5.34 t C/(hm2·a), which benefited from large-scale artificial vegetation restoration. In terms of measure types, vegetation measures acted as the leading approach for carbon sink promotion, achieving a cumulative carbon sequestration of 3004.93 t C through the synergistic carbon fixation of aboveground vegetation and underground soil. Engineering and temporary measures provided critical guarantees for passive carbon sequestration, with a total retained carbon of 1878.59 t C by effectively inhibiting soil erosion and reducing organic carbon loss. Conclusions Targeted soil and water conservation measures can significantly improve the carbon sequestration capacity of production and construction projects in ecologically fragile dry-hot valley regions. The constructed evaluation system provides a reliable and standardized methodological reference for carbon sequestration accounting of similar hydropower and engineering projects. Vegetation measures exhibit sustainable and stable long-term carbon sequestration advantages owing to persistent vegetation community succession, while engineering and temporary measures serve as essential defensive means to control soil carbon loss and guarantee regional carbon sink stability.