After only 40 years of development, Wal-Mart has become the largest private employer in the United States and the largest chain retailer in the world. The root of its mysterious success lies in the simple but difficult slogan-always low price, always. The main reason for the success of this slogan is to strictly control the cost of each link in the supply chain and sell products at the lowest price to win as many consumers as possible. The most important lesson that retailers can learn from Wal-Mart is to learn its supply chain management methods.