Effects of chlorine ion (Cl^-) concentration and current density on Microcystis aeruginosa’s growth inhibited by low-amperage electric current were investigated. The results showed that active chlorine played an important part in algae growth inhibition. When the algal solution was electrolyzed under the same condition, the growth of algae cells could not be sustainably inhibited unless sufficient amount of active chlorine could be generated in the electrolyte. The efficiency of electrolytic inhibition on algae increased with the increase of Cl^- concentration when Cl^- concentration was changed in the range of 0-18 mg/L, current density was 10 mA/cm² and electrolysis time was 15 min. When Cl^- concentration was not less than 12 mg/L, the growth of algae cells would be sustained inhibited. The efficiency of electrolytic inhibition on algae would also be increased with the increase of current density when current density was changed in the range of 0-20 mA/cm², Cl^- concentration was 18 mg/L and electrolysis time was 15 min.