The invention provides a late-stage fortified feed for fattening pigs and a preparation method thereof. The fortified feed is prepared from corn, soybean meal, fermented soybean meal, rapeseed meal, vitamins, trace elements, immunomodulator, anti-stress agent and other raw materials by crushing, mixing, granulating and other processing modes. From the perspectives of nutrition and immunity, the invention changes the traditional feed for fattening pigs, reduces the animal stress and enhances the proteinosis of pigs, thereby meeting the market requirements for feed safety, good body types of pigs, high meat factor and the like.