Abstract: Benzene, toluene, ethylbenzene and xylene(BTEX)are typical organic pollutants in coal chemical wastewater, which were difficult to be biodegraded under normal conditions, and were often removed by chemical means in the actual production process. This study based on the strong oxidizing free radicals generated in the process of ozone oxidation, used ozone oxidation technology to remove BTEX in simulated wastewater. The effects of pH value, temperature, ozone dosage and ozone dosing mode on the degradation of BTEX were investigated. The reaction mechanism of degradation by ozone was explored by using tertiary butanol as hydroxyl radical inhibitor and free radical dismutase as superoxide radical inhibitor. The results showed that the degradation effect of BTEX was the best when pH was 8, reaction temperature was 30 ℃, ozone dosage was 3.5 g/L and ozone dosage mode was countercurrent. The existence of superoxide radicals and hydroxyl radicals were the fundamental reason for the effective removal of BTEX from water by ozonization.