The invention discloses a vaccine for preventing porcine reproductive and respiratory syndrome. The vaccine provided by the invention comprises active ingredients consisting of NSP polypeptide and SP polypeptide, wherein an amino acid sequence of the NSP polypeptide is shown in the sequence 3 in a sequence table; and the amino acid sequence of the SP polypeptide is shown in the sequence 1 in the sequence table. The vaccine is prepared by uniformly emulsifying the NSP polypeptide, the SP polypeptide and a Freund adjuvant, and has the characteristics of application to the prevention of the porcine reproductive and respiratory syndrome, security, effectiveness, low cost, easy preparation and suitability for large-scale popularization and application.