China has the largest number and species of yak in the world. For some populations, the biological characteristics of yak milk are significant. It shows higher contents of protein, fat, lactose, minerals and vitamins compared to cow and goat milk. The contents of essential amino acids, essential fatty acids, lactose and minerals are similar to those of human milk. In addition, yak milk has some functional fat acids such as eicosapntemacnioc acid and docosahexaenoic acid, which are absent in cow and goat milk. From the viewpoint of food safety, yak milk specific protein is less likely to cause allergies and more easily digested and absorbed than cow milk. Safety evaluation experiments and population studies of conjugated linoleic acid show no side effects. Yak milk is expected to add new varieties in the field of infant formula milk by its unique nutrition and safety.