The invention belongs to the technical field of biology, and particularly relates to a high-pathogenicity porcine reproductive and respiratory syndrome heat-resistant protective agent live vaccine anda preparation method thereof. The heat-resistant protective agent live vaccine is high in aging resistance, the loss rate after storage for 7 days at 37 DEG C does not exceed 1 titer, and after the vaccine is stored for 18 months at 2-8 DEG C, the titer of the vaccine is reduced a little, so that the problems of energy waste and storage inconvenience caused by the fact that the vaccine needs to be subjected to frozen storage in the transportation and storage processes are effectively solved; through a high-pressure sterilization cabinet used in the preparation method, by arranging a shell, aleakage tank and a reaction tank, automatic weighing of raw materials of a heat-resistant protective agent is effectively achieved, rapid dissolving and uniform mixing of all the raw materials are achieved, meanwhile, the interior of the reaction tank can be automatically heated and pressurized, and finally the heat-resistant protective agent is prepared; and the preparation process is comprehensively and mechanically carried out, the cleanliness is relatively high, the influence of human factors is reduced, and the efficiency is relatively high.