Yak milk is the main source of dietary protein, fat, and micronutrients for Tibetan residents, who live at a high altitude and oxygen-deficient environment. The anti-hypoxia activity of yak milk powder (YMP) was investigated in mouse hypoxia models, using the normobaric hypoxia test, sodium nitrite toxicosis test, and hematological parameters analyses. The results showed that YMP could prolong the survival time under both normobaric hypoxia and sodium nitrite toxicosis conditions by 15.7%–17.3% and 13.9%–15.1%, respectively, and increase the levels of red blood cells (RBC) and blood hemoglobin (Hb). Furthermore, YMP was better than cow milk powder (CMP) in anti-hypoxia activity. YMP could be explored as a novel anti-hypoxia functional food ingredient.