S-Thanatin is an insect antimicrobial peptide with potent broad-spectrum antibacterial activity. S-Thanatin can inhibit the activity of Gram-negative bacteria, Gram-positive bacteria, and fungi, without cytotoxicity. The antibacterial activity of S-Thanatin is not affected by PH value, but monovalent cations (Na + /K + ) can reduce its antibacterial activity against Gram-negative bacteria in a dose-dependent manner.