Abstract: The Fenton method was applied to the treatment of acrylic fiber polymerization wastewater. The influences of the agentias and reaction conditions on removal efficiency were investigated, the action mechanism was analyzed, and the key controlling factors in the reaction course were determined. The indicator COD_Cr was used to determine the roles of influence in the agentias and reaction factors. The results showed that the degree of influence in the experiment was c(H₂O₂) > t > pH > c(Fe^2+). The optimal operating conditions tested were as follows: c(H₂O₂)0.2 mol/L, c(Fe²⁺⁾28.8 mmol/L, pH2.5, t150 min. Under these conditions, influent concentrations, effluent concentrations, and removal efficiencies of ρ(COD_Cr), ρ(BOD₅) and ρ(acrylonitrile) were 1 200.0 mg/L, 242.1 mg/L, and 97.4 mg/L; 301.6 mg/L, 110.0 mg/L, and 0 mg/L; and 74.9%, 55.0%, and 100.0%, respectively. The biodegradability of acrylic fiber polymerization wastewater was improved obviously by ρ(BOD₅)/ρ(COD_Cr) increasing from 0.2 to 0.36, and the particular pollutant, acrylonitrile, was removed efficiently.