In this paper, using the method of H₂O₂ – micro-electrolysis / MnO₂ to treat the papermaking waste water, the effect of initial pH of raw water, total iron and carbon, proportion of iron and carbon, hydraulic retention time, the amount of MnO₂ as well as H₂O₂ dosing quantity in micro—electrolysis unit were investigated. The results show that the initial pH was 3.0, the dosage of iron and carbon was 20 g/L, the MnO₂ dosage was 2.5 g/L, H₂O₂ dosing quantity is 0.55 g/L, the proportion of iron and carbon was 1:1 and the reaction time was 50 min, under these conditions, the removal rates of COD、SS、ammonia nitrogen, total phosphorus and BOD₅ were reached to 88%, 98.4%, 85%, 98% and 52% . At the same time, biodegradability increased from 0.32 to 0.81, the pollution load of subsequent biochemical treatment process was reduced.