The invention discloses a feed additive capable of improving lean meat rate of pigs. The feed additive comprises the following components: whey protein, yeast hydrolysate, probiotics, prebiotics, digestive enzyme, L-carnitine, capsaicine, garlic powder, a green tea extract and a green plum extract. Compared with the existing feed additive, the feed additive capable of improving the lean meat rate of the pigs has the advantages that green, safe and non-toxic effects of all the components are achieved, and the human health is facilitated, and drug residue and food chain transmission can be avoided; after the pigs are fed by the feed additive, the immunity of the organism and the disease resistance of the pigs are improved, the muscle composition and the absorption of fat are improved, the fat of the pigs is promoted to be decomposed, muscle building and weight increment are realized in a healthy state, and the lean meat rate of a pig carcass can be improved; a test for comparing fattening pigs and piglets in the aspects of production performance and meat quality proves that after the feed additive is adopted, the indexes such as the average daily gain of the pigs, the feed conversion ratio, the eye muscle area, the lean meat rate and the muscular tissue are obviously improved, and the indexes such as backfat thickness, diarrhea rate, death rate, drip loss and the like are obviously reduced.