Lactose is a unique disaccharide which exists in the mammal breast milk and also the main carbohydrate in milk (more than 99.8% of the total sugar content). Normal fresh cow milk contains 4.8%˜5.2% lactose, which is about 52% of non-fat cow milk solids and about 70% of the solid whey. The Medical Encyclopedia, a service of the U.S. national library of medicine and the National Institutes of Health, provides that, unless lactose is decomposed by enough lactase in the small intestine when it enters into the alimentary tract, lactose intolerance, including symptoms such as abdominal distension, abdominal pain, or diarrhea, occurs. Lactose intolerance happens more often in Asian, African, and Latin American. Lactose mainly comes from dairy products. In order to avoid lactose intolerance, people usually choose to change their diet style, avoid eating or drinking milk or dairy product. However, as reported in the World Journal of Gastorenterol., Vol. 12, No. 2, pages 187-191 (2006), quitting milk or dairy product can lead to absent diet structure and body nutrition imbalance. In order to solve the problem caused by having milk, a method mentioned in U.S. Pat. No. 6,881,428, U.S. Patent Application Publication 20050170044, and European Food Tech Award to Valio lactose free milk technology (2006/5/4) discloses that in nowadays milk processing, it is common to use lactase to hydrolyze milk lactose to decrease the lactose concentration and alleviate the discomfort associated with drinking milk. Unfortunately, this method produces glucose and galactose, the total molar concentration of which equal to that of the unhydrolyzed lactose, and the total sugar content is not reduced. Long-term or large-volume intake of this kind of milk will not help stabilizing diabetes patient's blood sugar. Removing the lactose of cow milk and decreasing total sugar content of cow milk are very important to ensure the consumer's good health. At present, there are methods for removing lactose from cow milk as reported in domestic or overseas publications. For example, U.S. Pat. No. 5,429,829 relates to a method of making flavorful de-lactose cheese products by using chymosin along with milk fermentation, however, this type of process makes the dairy product lose its nutritious whey part. U.S. Patent Application Publication 20050214409 discloses a method using membrane separation and column chromatography to remove lactose from milk which may reserve the nutritious whey part, unfortunately, the method is so inefficient that it is hard to be adopted in industrial production.