This invention provides a category of polypeptide that restrain HIV virus to mix together. According to the mechanism of action of HIV virus and adaptor molecule which is on the surface of cellular membrane in the process of membrane fusion, this invention designs an active polypeptide which can bind with virus surface glycoprotein gp41. Effect situs of mentioned polypeptide is at trimer NHR lateral 'long point' and bilateralis that is in gp41 molecule, it can effectively restrain reproduction of HIV virus. The polypeptide of this invention compared with present medicine, has small molecular weight, high activity, good water solubility. Using polypeptide that is mentioned by this invention can prepare medicine which can restrain many kinds of viral infection.