Cecropins B is an antibacterial peptide extracted from insects. It belongs to the spectrum antibacterial peptide. It has the advantages of good thermal stability and good water solubility. More importantly, the antibacterial peptide has little effect on eukaryotic cells, only on prokaryotic cells. And the diseased eukaryotic cells can be regarded as the most active antibacterial peptide among the known natural antibacterial peptides. Cecropins B consists of 35 amino acids, and there are a large number of basic amino acids in the sequence.