The present invention provides a polypeptide that is rich in leucine and used for preventing and restraining inflammation, and an application of same. The present invention further provides a method for preparing the polypeptide and a pharmaceutical composition containing the polypeptide. The advantage of the polypeptide comprises: small molecular weight, so as to permeate various eye tissue barriers; high water solubility, so as to have high dissolubility in neutral tears, aqueous humor and vitreous humor; and simple synthesis, so as to have a low preparation cost.