Abstract: The spatial distribution characteristics of nutrients and diffusion fluxes at the sediment-water interface were analyzed in the three sites of the Licun River estuary in the summer of 2010. The results showed that the nutrient contents in interstitial water were different within the investigated sites, which decrease with the distance from the inner Licun River estuary. The concentration of NH₄⁺-N was 26.21-53.10 mg/L, which was the main form of nutrients in interstitial water of sediment. The organic matter decomposition was completed in anaerobic condition. The nutrients concentration profile in sediment interstitial water was influenced by the concentration of organic matter and the oxidation-reduction environment. The diffusion of nutrients in tidal flat area was from pore water into overlying water, except NO₃^--N. The sediment in tidal flats was the important sources for nutrients in bottom water.