Abstract: CCR reformate is rich in mixed xylenes and usually contains some trace olefins, which could be removed by active clay. The application status of clay at the xylene refining tower of CCR unit and the principle of clay refining were summarized, the deactivation of clay was analyzed from the quality of clay, operation conditions and reaction severity of CCR process as well. To prolong the service life of clay, measures including optimizing the process flow of clay refining, optimizing reforming feed and reaction conditions, as well as optimizing the operation conditions of clay refining tower, were put into practice. Since then, the service life of clay prolonged from 30 d to 60 d and the loss of xylene cut down due to less clay substitutions.