Abstract: In order to analyze the variation status and molecular properties of subgroup J avian leukosis virus (ALV-J) in Northeast China, 12 strains of ALV-J were isolated from commercial egg-type chickens suffering from hemangiomas and myelocytomas of the region. The complete env gene, 3′untranslated region (3′UTR) and 3′ long terminal repeat (LTR) sequences were amplified, cloned and sequenced. Sequence analysis of the env gene, 3′UTR and 3′LTR revealed several unique genetic characteristics of 12 recent isolates. Phylogenetic trees showed that the 12 isolates from different flocks fall into three separated groups. Among 12 isolates, the 3 isolates were classed into group2 showing 120 bp deletion in the env gene and 2 isolates were classed into group3 showing recombination between earlier ALV-J and endogenous virus sequence. In addition, the intact E element was found in majority of isolates and highly conserved; within the 3′LTR, the direct repeat region (R) and the 3′unique region 5(U5) were well conserved; albeit U3 region exhibited high mutations, the transcriptional regulatory elements including C/EBP, CArG box, Y box, PRE box and TATA box were highly conserved. These results suggested that the deletion and recombinant in envelope gene has became new variation tendency of ALV-J in China, and the variation of the envelope gene and 3′UTR were probably important in tissue tropism changes and induce tumors.