The Photocatalyzed degradation of ethylene in the gas phase was investigated using titanium dioxide by Chemical Vapor Deposition. Photocatalysts were prepared by depositing anatase TiO2 film on alumina balls. The initial concentration of ethylene, reaction temperature, flow rate were the factors that had an effect on the decomposition of ethylene. The photocatalytic degradation of ethylene shows the degradation rate increases with decreasing initial ethylene concentration and total flow rate. The degradation rate increases with increasing reaction temperature.