Abstract: The ferriccarbon microelectrolysis was employed to pretreat the hot grinding wastewater from medium density fiberboard production. The effect of the pretreatment on the removal rate of COD, lignin and SS of wastewater was studied. According to the results of singlefactor experiments, the optimum technologic conditions were obtained, i.e., influent pH value was 3, V(Fe)∶V(C) ratio was 1∶1, dosage of Fe and C wastewater was 300 mL/L, reaction time was 80 min, coagulation pH value was 8.5 and sedimentation time was 120 min. Under this condition, the removal rate of COD, lignin and SS reached 74.24 %, 89.77 % and 91.27 %, respectively. It was also pointed out by the comparative experiment that the effect of coagulation and sedimentation was more important than that of microelectrolysis. They were the key factors in the whole pretreatment.