The chemical composition of sugars can be divided into monosaccharides, disaccharides and polysaccharides. Lactose is a disaccharide, and its molecular structure is formed by the condensation of one molecule of glucose and one molecule of galactose. Lactose is broken down into one molecule of glucose and one molecule of galactose by disaccharidase in the human body and absorbed and used by the body. Glucose is the only suitable sugar in the blood, and the blood sends glucose to every cell in the body, and the cells convert glucose into carbon dioxide and water and release heat energy. Lactose is the best sugar for children to consume, and there are sufficient lactase enzymes in children’s digestive tract to break down lactose, so it can be well broken down and absorbed and utilized. The lactose content in human milk, milk and goat milk is different. Human milk contains 7% lactose, milk contains 4.2% lactose, goat milk contains 4.6% lactose, and the lactose content in cow and goat milk are lower than human milk. The lactose content in human milk is not only higher and more stable than cow and goat milk, but also does not change due to changes in the mother’s food and does not fluctuate due to changes in blood sugar, so the composition is more stable. Lactose is the most abundant sugar in milk. 99.8% of the sugar contained in milk is lactose, and there are also small amounts of glucose, fructose and galactose. Lactose is easily soluble in water, and almost all of the lactose in milk is in solution, which is easy to digest and absorb.