Considering the complex composition of organic waste gas in chem. enterprises, this project adopts the principle of classification and quality treatment for process waste gas, and adopts the process of combination of absorption and adsorption to purify its waste gas, which achieving ultra-low concentration and reaching the standard of emission. The results showed that the concentration of methanol, sulfuric acid fog, SO_2, particulate matter and non-methane hydrocarbon at the outlet of the exhaust cylinder were 3.4, 7.5, 3.9, 18.8 and 19.6 mg/m∼3, resp. And the emission rates were 0.042, 0.097, 0.051, 0.319 and 0.333 kg/h, resp. They all meet the requirements of the new pollution sources of air pollutants in the discharge standard of the secondary standard(GB 16297-1996). The treatment capacity of the system is 17150 m∼3/h, and the operating cost is 655 yuan per day. For this kind of waste gas, the whole treatment system has many advantages such as simplicity, practicality and economy.