The invention belongs to the technical field of medicines, and in particular discloses application of an antimicrobial peptide Protegrin-1 for preventing and controlling porcine reproductive and respiratory syndrome. According to the invention, an antimicrobial peptide Protegrin-1 is chemically synthesized according to an amino acid sequence of reported Protegrin-1 firstly; then, antimicrobial activity of the antimicrobial peptide Protegrin-1 is proved through an escherichia coli resistant DH5 alpha experiment, and researches on the antivirus activity of the antimicrobial peptide to HP-PRRSV are made through qRT-PCR, Western-Blot, cell supernatant TCID50 detection, IFA and other methods; and further the antivirus mechanism of the antimicrobial peptide is explained in virus adsorption and entrance into cell processes. The antimicrobial peptide Protegrin-1 is expected to be used as a novel medicine for preventing and controlling porcine reproductive and respiratory syndrome.