The phosphorus stored in the sediments can be released into the overlying water, acting as internal source for lakes. pH isone of the important factors influencing phosphorus release. In this paper, phosphorus fractions and the effect of pH on P release (48h)were investigated for the sediment from Meiliang Bay, Lake Taihu. The pH of the system was controlled with different buffersolutions. The release characteristics of phosphorus were influenced markedly by the pH condition. Specifically, acidity (pH=2.0) andalkalinity (pH=9.5, 11.8) conditions were more beneficial for phosphorus release than the neutral pH(pH=7.2) condition. The amountof phosphorus released from the sediments under alkalinity conditions (pH=9.5, 11.8) was about 4 folds than that in the acidity(pH=2.0, 4.6) and neutral condition when the release of phosphorus tended to be stable(14h). There had been distinct difference forthe phosphorus speciation in the sediments of different simulation system. With the analysis to the phosphorus speciation ofsediments after release experiment, it can be concluded that acidic condition can enhance Ca-bound phosphorus release, whereasalkaline condition can promote the release of Fe-bound phosphorus significantly. Fe-bound phosphorus is the key form of phosphorusrelease in Meiliang Bay of Lake Taihu. pH value is an important mechanism of influencing phosphorus content and eutrophication.