Abstract:In order to study the effect of O3 inactivating Microsystis aeruginosa in water,different factors (the ozone dose, time, pH, temperature, turbidity and cell density) which might influence the inactivation were investigated by using neutral red staining assays. The results indicated that the inactivated rate of O3 affecting Microsystis aeruginosa increased as the ozone dose and time prolonging obviously. When the turbidity was 0.5 to 20.0NTU,temperature was 5 to 35℃, pH was 6.0 to 9.0, the turbidity was lower, the higher inactivating ratio could be received. With the increasing of temperature, the inactivating effect was decreased. The ability of O3 inactivating Microsystis aeruginosa was stronger under acidic condition than it was in alkali circumstance. If cell density increased, the inactivation efficiency decreased significantly. The initial algal concentration also influenced the treatment efficiency. If cell density increased the inactivation efficiency decreased significantly. If the initial algal concentration was 1.0×107 cells/L, the ozone dose 2.0 mg/L and the time was more than 40 min, the ratio of inactivation could exceed 99.0% and the capability of propagator was zero during disinfecting drinking water.