Abstract: An identification and an application of an ALV-J MHC-B2 restrictive epitope peptide are provided, which belong to the field of genetic engineering. An amino acid sequence of the provided ALV-J MHC-B2 restrictive epitope peptide is selected from SEQ ID NO:1, SEQ ID NO:2 and SEQ ID NO:3. An application of the ALV-J MHC-B2 restrictive epitope peptide in preparing an ALV epitope-based vaccine is provided. Restrictive motif of B2-haplotype chicken MHC class I molecule binding peptides is identified by in vitro elution assay. Potential epitopes in four proteins expressed by ALV-J are systematically screened by motif. The immunogenic B2-haplotype chicken ALV-J T-cell epitope peptides are identified by functional validation. It provides a material and theoretical basis for the research and development of ALV epitope-based vaccines.