After the Cansolv exhaust gas treatment plant was put into operation, excessive organic matter was generated, resulting in a drop in the operating efficiency of the membrane unit of the waste water treatment plant. The above event gave rise to the issue of clogging and foaming of the evaporation crystallization unit . The combination of ozone catalytic oxidation and chemical catalytic oxidation was selected to reduce the levels of the COD (Chemical Oxygen Demand，COD) and sulfite in the waste water of the Cansolv exhaust gas treatment plant. After the ozone catalytic oxidation unit was put into operation, the COD level of the waste water treatment unit decreased and the foaming of the salt slurry was well alleviated. The reduction of COD level in waste water has a very obvious optimization effect on the operation of RO reverse osmosis and evaporation crystallization unit, which ensures the normal operation of the waste water treatment plant.