Yak milk is light yellow and has a strong smell. Due to the lack of reasonable processing and people's inadaptability to the smell of yak milk, it is a difficult problem in the processing and sales of yak milk, so the smell of yak milk is an urgent problem to be solved. Most people tend to think that low-grade volatile fatty acids (fatty acids below c 14) in milk are the main reasons for milk turbidity. In addition, the formation of milk flavor is also directly related to the variety, age, production season, feed type during lactation, feeding mode, storage mode of raw milk, lipase activity in raw milk, total number of bacteria and other factors. The content of lower fatty acids in yak butter is lower than that in milk. In the master's thesis, Tuo Yanfeng determined the fatty acid composition of Holstein milk and yak milk, and concluded that the content of lower fatty acids in yak's fatty acids was lower than that of Holstein milk, but yak milk was more smelly than ordinary milk in sense, and the reason was not clear. Therefore, through the study of volatile compounds, lipases and microorganisms in yak milk, the causes of the odor formation of yak milk were inferred, and then the effective methods to remove the odor of yak milk were found.