Abstract: Avian leukosis is one of the main chicken tumor diseases.It causes considerable economic loss for poultry farmers.A new,rapid diagnostic mehtod applying the real-time florescence quantitative polymerase chain reaction(PT-PCR)was developed for detecting the avian leukosis virus subgroup J(ALV-J).A set of subgroup J special primers for gp85 gene was used.Validations on repeatability,specificity and sensitivity of the methodology showed its potential applicability for clinical diagnosis of ALV-J.