Dichloroacetic acid (DCAA) is one of Haloacetic acids (HAAs) which are the main disinfection by-products (DBPs) produced by drinking water chlorination. The irradiation degradation of DCAA by 60Co ?-rays in different anaerobic dilute aqueous solutions was studied. The concentrations of DCAA and chloride ion in the system were analyzed by IC before and after irradiation. The influences of absorbed dose and irradiation aura on the elimination of DCAA were investigated, respectively, by comparing the removal ratio of DCAA with concentration of chloride ion formed. The irradiation degradation mechanism was deduced preliminary according to the experiment results.Cited