Disclosed are a fusion peptide of CD4 helper T cell epitopes, a nucleic acid encoding the same and an immunogenic composition comprising the same. The epitope fusion peptide comprises a cytomegalovirus epitope and an influenza virus epitope. The epitope fusion peptide can substantially improve the level of cellular immune response to a target immunogen, particularly a weak immunogen, and is an effective means for overcoming the immune tolerance of immune system to an antigen, particularly to a tumor antigen or an infection-related antigen, and is suitable for efficiently enhancing the efficacy of vaccine.