Microcystin-LR attracts attention due to its high toxicity, high concentration and high frequency. The removal characteristics of UV/H O and O /H O advanced oxidation processes and their individual process for MC-LR were investigated and compared in this study. Both the removal efficiencies and rates of MC-LR as well as the biotoxicity of degradation products was analyzed. Results showed that the UV/H O process and O /H O were effective methods to remove MC-LR from water, and they two performed better than UV-, O -, H O -alone processes under the same conditions. The effects of UV intensity, H O concentration and O concentration on the removal performance were explored. The synergistic effects between UV and H O , O and H O were observed. UV dosage of 1800 mJ·cm was required to remove 90% of 100 g·L MC-LR, which amount significantly decreased to 500 mJ·cm when 1.7 mg·L H O was added. 0.25 mg·L O , or 0.125 mg·L O with 1.7 mg·L H O was needed to reach 90% removal efficiency. Furthermore, the biotoxicity results about these UV/H O , O /H O and O -alone processes all present rising trends with oxidation degree of MC-LR. Biotoxicity of solution, equivalent to 0.01 mg·L Zn , raised to 0.05 mg·L Zn after UV/H O or O /H O reaction. This phenomenon may be attributed to the aldehydes and ketones with small molecular weight generated during reaction. Advice about the selection of MC-LR removal methods in real cases was provided.