Abstract: The effects of adding sodium bicarbonate in the feed of yak with appropriate amount on the milk yield and related indices of yak were studied. The results showed that the milk yield of yak in three test groups had no significant change with control group, pH of yak milk had no significant change before and after the experiment. The milk fat percentage of yak in test group 1, 2, 3 significantly increased 2.52%, 2.95% and 3.08% respectively.