A microcystin-degrading strain named as T1 was isolated from Taihu Lake sediment. Based on the morphological observations, physiological-biochemical analysis and tests for biodegradability, the study results showed that the degrading rate of MC-LR reached 60%~70% by T1 strain after 48 hours reaction. The optimal treatment parameters of T1 strain were as follows: pH 7.0, inoculum concentration 8% and rotating speed 120 rpm. Moreover, the concentration of carbon source has some stimulating effect on the degradation of MC-LR. The study has significant reference and actual application value for the biodegradation of MC-LR in eutrophic water.