Effect with growing of submerged macrophytes on NH₄⁺-N and PO₄^3--P concentration in the interstitial water was studied by using undisturbed core samples in Lake Taihu,and analyzed the relationship between biomasses of submerged macrophytes and amount of nitrogen and phosphorus release. The results showed that concentration of NH₄⁺-N from 0-5 cm in interstitial water was gradually reduced by the biomasses increase of submerged macrophytes,and amount of nitrogen release is distinctly negative correlated with biomasses of submerged macrophytes;The PO₄^3--P concentration in interstitial water change was me peak tendency by the growing of submerged macrophytes,indicating that there was no distinct corlationships between amount of phosphorus release and biomasses of submerged macrophytes. There mingt exisf different biogeochemcal mechanism of the absorption of nitrogen and phosphorus by submerged macrophytes