Abstract: Ammonium(NH4+) is the preferred nitrogen form for plankton, its regeneration(REG) and potential uptake(Upot) are related to primary productivity and growth of organisms in water ecosystems. In this study, NH4+ recycling rates in the littoral zone of the middle reach of the Yangtze River were studied by using the isotope dilution method. Results showed that the REG rates in the middle reach of the Yangtze River were 0.12-1.62 μmol/(L·h), the Upot rates were 0.21-2.35 μmol/(L·h), and the community biological NH4+ demand(CBAD) rates were 0.08-0.75 μmol/(L·h). Moreover, along with the flow direction of Yangtze River, NH4+ recycling rates showed significant decreased trend from Yichang to Poyang Lake estuary(p<0.05). Statistical analyses showed that chemical oxygen demand(COD) and suspended solids(SS) are the main factors influencing the NH4+ recycling rates in the middle reach of the Yangtze River. During the study area, the REG rates accounted for 43.1%-76.0% of the Upot rates, with a mean value of 58.5%±8.5%. This indicated that REG is the main source of NH4+ in the process of Upot by the biological communities in the middle reach of the Yangtze River. NH4+ produced by REG process is 2 times higher than that of water column TN loads, indicating that REG plays an important role in supporting primary productivity and maintaining nitrogen internal circulation.