Arginine is also known as protein amino acid.Traditionally, arginine is not considered as an essential amino acid for sows and piglets, but modern pigs grow faster, have higher lean meat rate, and have more fetuses.Therefore, there is a higher physiol. demand for arginine. A large number of studies have shown that adding 0.5% to 1% arginine to the diet can improve the performance and reproductive performance of sows and piglets.In this paper, the physiol. metabolism and nutritional function of arginine in sows and piglets were discussed.