The invention provides novel polypeptin with biological prevention and control and medical application potential values, and application thereof. The polypeptin has a structure shown in a formula (I). The invention has the main advantage of providing the polypeptin with toxicity lower than that of polymyxin B and biological prevention and control and medical application values, and a preparation method and application thereof. In-vitro experiments show that the compound has a remarkable inhibiting effect on gram-positive bacteria, gram-negative bacteria and fungi; and in-plate cultivation experiments show that the compound has certain prevention and control effects on a plurality of fungal plant diseases and particularly has the most remarkable prevention and control effects on rhizoctonia solani.