The model experiment of aerobic decomposition of Microcystis spp.(mainly including M.aeruginosa, M.flosaquae) in Taihu Lake was studied.The results show: the decomposition can be approximated by first-order kinetics.The particulate matter and concentration of particle phosphorus are decreased exponentially.The rates of decomposition are 0.227d^-1 and 0.088^-1、respectively.After 32 days, experiment, the total dissolved phosphorus (TDP) accounts for 53% of total phosphorus (TP), and phosphate (PO₄^3-) is the main component of TDP.During the aerobic decomposition of Microcystis, the water quality and the cycling of nutrient, especially the release of PO₄^3- may not be overlooked.