Sulfur and iron are important biogenic elements in peatland. Their participation in biogeochemical process is of great significance to carbon cycle of peatland. This study aimed to investigate impact of key elements on carbon emission of ombrotrophic peatlands, at top broad position (TBP) and top slope position (TSP) sites. The concentrations and distributions of carbon as DOC, GHG (particularly CH₄ and CO₂) were estimated through an in-situ collection of pore water and soluble gas in peat profile. Combined with the geochemical characteristics of sulfur (S) and iron (Fe) elements, their impacts on carbon emissions from peatland were discussed. The results showed that (1) the concentrations of total reduced inorganic sulfur (TRIS) in TBP first increased and then decreased with depth. The average concentration of the upper part was much higher than that of deeper part. The sulfate reduction in the upper part was strong. Combined with the concentrations and distributions of ferrous iron and hydrogen sulfide (H₂S) in the corresponding range, it is inferred that H₂S is mainly generated by bacterial sulfate reduction (BSR) in this range. Meanwhile, during the diffusion process of H₂S in pore water, it is easy to combine with ferrous iron into FeS. And then stable FeS₂ was formed. The reaction process slowed down at about 60 cm. (2) The DOC had a strong correlation with ferrous iron and sulfate in TBP and TSP because the fluctuation of groundwater level affects the redox degree and microbial activity. DOC had a significantly positive correlation with ferrous iron in the two sampling sites, indicating that iron oxide was reduced to dissolved ferrous iron in the anaerobic environment, and the organic carbon combined with ferrous oxide was released into pore water, resulting in the increase of DOC concentration. DOC had a negative correlation with sulfate in TBP, indicating that the acidity was consumed in the reduction process of sulfate as electron acceptor, and the pH value increased, which enhanced the activity of microorganism. Thus the concentration of DOC was increased. (3) The concentrations of CH₄ and sulfate, CH₄ and TRIS in the two sampling sites showed opposite trends with depth on the profile, indicating that increasing sulfate input and sulfate reduction would inhibit the formation of CH₄. The CO₂/CH₄ ratios of the two sampling sites were greater than 4, indicating that sulfate as an alternative electron acceptor may shift carbon mineralization under anaerobic conditions to more CO₂ and less CH₄ production. In addition, high concentration of ferrous iron can inhibit the formation of CH₄, and low concentration of ferrous iron can promote the formation of CH₄. But ferrous iron had a weak effect on the formation of CO₂. The results also show that sulfate concentration plays a dominative role over ferrous iron in CH₄ and CO₂ production. In this study, the effects of underground geochemical factors such as sulfur and iron on carbon emissions were also discussed, which provided more rigorous theoretical support for the correction of carbon emissions from peatlands.