Four bacterium isolated from Microcystis surrounding irx Taihu Lake were identified. Three of them (X, Y2，D) arc Pscitdomonas spp.，the other one (H) is Bacillus sp. Under the same culture condition, their growth curves were determined as follows： the lag phase of X，Y2，D and H lasts respectively less than 0. 5h，less than 0. 5h, lh and lOh; the stationary phase starts seperately at about 30h，30h，20h，60h.