Most studies related to nitrogen flux across the sediment-water interface were focused on the effects of aquatic environment factors on nitrification rates, while there is no information about the effects of nitrification on other factors. In this research, laboratory experiments have been conducted to investigate nitrogen flux from the sediment cores collected from the Three-Gorge Reservoir of the Yangtze River (China). The effects of the nitrification process on the fluxes of ammonium (NH4+), nitrite (NO2-) + nitrate (NO3-), and total organic nitrogen (TON) across the sediment-water interface have been examined. The release flux of TON accounted for more than 50% of the total nitrogen. The nitrification process stimulated the growth of ammonifying bacteria and accelerated the release of NH4+ and NOx- from the sediment cores during the 40-day incubation and TON during the first 10-day incubation. A 25% increase in the nitrification rate increased the release rates of NH4+ and TON by approximately two times during the first 8-day incubation.