The aim of this study is to analyze the major allergens in yak milk. The Balb／C mice were sensitized by intraperitoneal injection with yak milk protein. After the last sensitization, blood was collected through the eyes for antibodies and histamine determinations. The lymphocytes derived from spleens were cultured under sterile condition. The major allergens in yak milk were analyzed using western-blotting. The results showed the major allergens in yak milk were β-lactoglobulin, α-casein, and β-casein, and the allergenous extent was β-lactoglobulin>α-casen>β-casein. The higher content of IL-4, IL-5 and lower IFN-γ produced by the spleen lymphocyte proliferation indicated that the yak milk protein was the Th2 response.