The sediments are the important reservoirs of mineral nutrients and sedimentary P can function as a main internal P source for the lakes. Part of the P in the sediments can be released to the sediment interstitial water by decomposing or dissolving in the form of phosphate. Subsequently, the phosphate in the interstitial water may be released to the overlying water by diffusion or re-suspension of surface sediments. The factors which affect P release from sediments and the release mechanisms are briefly summarized in this paper.