Abstract:CLT acid production wastewater is a type of difficultly biodegraded organic wastewater. The wastewater contains high organic pollutants concentration and salinity. Fenton reagent was used for the pretreatment of CLT acid production wastewater. The parameters that affect the treatment efficiency, such as H2O2 and FeSO4·7H2O dosage and the molar ratio, pH and reaction time, were investigated and determined in this study. The results showed that the optimum conditions for the reaction were as follows: initial pH values of 3~4, 30min rection time, 20mL/L H2O2 dosage and 10g/L FeSO4·7H2O dosage. The H2O2 was just entirely consumed and the COD removal was 56% in the optimum condition. Fenton oxidation pretreatment can significantly improve the biodegradability of the production CLT acid wastewater. The BOD5/COD value of the raw wastewater was 0.075 while the value increased to 0.37 when treated by Fenton reagent in the optimum condition. 6 benzene series materials can be detected in the raw wastewater by GC-MS. However, no featured organic pollutants can be detected when the wastewater was treated by Fenton oxidation. The pretreated wastewater can be further treated by biological technologies. The Fenton agent is suitable for the pretreatment of CLT acid production wastewater.