The invention discloses a compound premix additive for improving bone development of replacement gilts. The compound premix additive is prepared from, by weight, 30-40 parts of vitamin complex, 40-60 parts of trace element composite, 30-40 parts of choline chloride, 40-60 parts of L-lysine hydrochloride, 10-15 parts of DL-methionine, 5-10 parts of L-threonine, 120-150 parts of calcium hydrophosphate, 120-150 parts of monocalcium phosphate, 250-280 parts of limestone powder, 90-110 parts of salt and 85-265 parts of bran. By adoption of the compound premix additive, bone toughness and strength of the replacement gilts can be improved, reserve quantity of nutrients such as vitamins, trace elements and the like in the replacement gilts is increased, and accordingly occurrence rate of the foot-and-leg disease of the gilts is decreased, health of feet and legs of the gilts is protected, and lives of the gilts are prolonged.