The invention relates to a premix for improving the production performance of a sow as well as a preparation method and application of the premix. The premix is prepared from the following components in parts by weight: 10-30 parts of arginine, 5-12 parts of L-carnitine, 1-15 parts of folic acid, 5-20 parts of fructose-oligosaccharide, 50-150 parts of astragalus polysaccharide, 50-150 parts of butyrin, 50-120 parts of bifidobacterium bifidum probiotic powder, 0.1-0.2 part of chromium picolinate and the balance of carrier based on 1,000 parts by weight, wherein the premix is added to a basic ration of the sow at 1-4% of total mass of the basic ration of the sow. Compared with the prior art, the premix has the advantages that the sow feed intake and the lactation yield can be effectively promoted by the premix; the weight loss and the backfat loss of the sow at the lactation period can be reduced; the heat interval after weaning is shortened; the whole production performance of the sow is improved; and the problems of insufficient sow feed intake, insufficient milk, postpartum diseases and low production performance are effectively solved.