Denitrification(DNF) and dissimilation reduction to ammonium(DNRA) are two major pathways for the dissimilatory nitrate reduction processes. Denitrification is the dominant nitrogen loss process that removes nitrate in the water column, while DNRA reduces nitrate to ammonium which is still a biologically available form in aquatic environments. The nitrate served as electron acceptor during denitrification and DNRA processes, and the balance of two processes depends on environmental factors. The study on rates of denitrification and DNRA plays an important role in understanding the fate of nitrate and its dynamic. In this study, intact sediment cores were collected in three wetlands of Lake Poyang and Lake Chaohu. Denitrification and DNRA rates were determined by continuous-flow experiments combined with ¹⁵N isotope-tracing techniques to investigate their contributions to total nitrate reduction. The results showed that denitrification and DNRA rates ranged from (6.36±2.57) to (99.98±14.05) μmol/(m²·h) and (0.51±0.45) to (79.82±6.08) μmol/(m²·h), respectively. DNRA rates were enhanced significantly with increasing pollution degree as well as the DNRA/(DNF+DNRA) ratio, which indicates that the contribution of DNRA to total nitrate reduction in these wetlands was affected by nitrate loadings. Uncoupled nitrification-denitrification was the dominant nitrogen removal process in Lake Chaohu, and coupled denitrification was the dominant process in the Lake Poyang.