Nitrogen pollution in lakes poses a significant challenge. Historically, researches on nitrogen removal from lake sediments has concentrated on denitrification and anaerobic ammonium oxidation(anammox) processes. The recent discovery of anaerobic ammonium oxidation coupled to iron(Ⅲ) reduction (feammox) had expanded our understanding of nitrogen transformation pathways, leaving the specific contributions of each nitrogen removal process in lake sediments still unclear. This study quantitatively assessed the rates of denitrification, anammox, and feammox in the sediments of 18 lakes located in the middle and lower reaches of the Yangtze River utilizing the ¹⁵N stable isotope tracing technique. We then estimated the nitrogen removal efficiency attributed to each process. The findings revealed that the average denitrification, anammox, and Feammox rates in winter were (2.38±0.80) mg/(kg·d), (0.06±0.04) mg/(kg·d), and (0.015±0.025) mg/(kg·d), respectively, contributing to 96.5%±2.4%, 2.7%±2.0%, and 0.8%±1.4% of nitrogen removal. During summer, the rates were (2.54±1.04) mg/(kg·d), (0.12±0.06) mg/(kg·d) and (0.005±0.005) mg/(kg·d), respectively, with contributions of 95.0%±3.4%, 4.8%±3.2%, and 0.2%±0.3%. Despite the relatively minor role of feammox in overall nitrogen removal, its significance in NH⁺₄ elimination is noteworthy, accounting for 15.5%±23.4% in winter and 13.4%±22.4% in summer. Notably, in Lake Honghu, Lake Xiliang, and Lake Futou in winter, and in Lake Poyang in summer, feammox's contribution to NH⁺₄ removal exceeded that of anammox, underscoring the importance of feammox in sediment NH⁺₄ removal. Multivariate statistical analysis suggested that pH, nitrate, total organic carbon, and total inorganic carbon were key factors influencing feammox activity. This study enhanced our comprehension of nitrogen cycling pathways within lake ecosystems, elucidated the transformation processes and environmental fate of nitrogen, and provided crucial theoretical support for managing nitrogen and controlling eutrophication in these environments.