Abstract: In August 2009, A Hyline layer chicken flock was infected at Zoucheng in Shandong Province, and mortality was up to 7% at age of 160day. Three of illness chickens were presented and diagnosed as avian leukosis virus subgroup J (ALVJ) infection by gross and histopathological observation, PCR and immunohistochemistry, etc. Histopathological observation showed that hemagioendotheliosarcoma existed single in No.1 chicken; fibrosarcoma was concurrent with myelocytomas in No.2 chicken. No cytopathic effect was found on the cultured DF1 cells inoculated with sick bird liver samples and of which supernatants fluid was positive for ALV p27 antigen by ELISA test. Phylogenetic analysis showed that gp85 nucleotide sequences of the isolated strain had the highest homology with that of the prototype HPRS103 (94.1%). Our study demonstrated that ALVJ is a multipotential oncogenic virus. The mechanism of tumor spectrum expansion induced by ALVJ in layer flock needs to be further studied.