Abstract: This article elaborates the theory of VAM oxidation which is used to analyze and test the field device. It is shown that the volume of VAM (60 000 m³/h) which is oxidized is large; oxidation efficiency increases with the increasing of VAM concentration; the device shows well at the fluctuation of air volume and VAM concentration; the overheating vapor production and temperature is improved with the increasing of inlet VAM concentration, when the vapor pressure keeps stable.