The T4 phage display system is highlighted by its ability to fuse the two exogenous peptides or proteins in completely different nature with coat proteins, SOC (9 ku) and HOC (40 ku), and directly display them on the surface of T4 phages, avoiding protein denaturation or loss caused by purification. T4 phages are assembled in host cells and do not require a secretory pathway, so they can display peptides or proteins of various sizes. When using recombinant T4 as a vaccine, one can display the target antigen on the surface of an empty capsid, indicating the system's promising prospect in biosafety.