IL-18 has a certain difference in amino acid composition from other cell-penetrating peptides. The sequence contains relatively more hydrophobic amino acids. Its penetration mechanism mainly relies on the binding of the guanidine group on arginine to the cell membrane and at the same time passes through the α- The helix binds to the cell membrane and gradually penetrates the cell membrane as the concentration of the peptide increases. When using chemical methods to synthesize peptides, different types of condensing agent systems need to be selected for IL-18 sequence.