Theoretical simulation calculations of tetrachloroethylene (PCE) decomposition in air mixtures under electron beam (EB) irradiation have been carried out based on the experimental results. A computer code Kinetic and a Gear method were used and 324 reactions and 76 species were considered. From calculated results, we learn that more than 99% PCE is decomposed at 4.4kGy dose when the initial concentration of PCE is 322ppm; concentrations of inorganic carbons (CO+CO 2 ) increases with the dose, and the relative carbon concentration of inorganic carbons is about 17% at 13.1kGy; phosgene (COCl 2 ) and trichloroacetyl chloride (CCl 3 COCl) are predicted as main organic products and are confirmed by the experimental results. The good agreement is obtained between the calculated results and the experimental data.