The purpose of this study was to investigate the nutritional composition and volatile substances changes of yak yogurt under refrigeration storage. The nutritional composition and volatile substance were measured by amino acid analysis, fatty acid methyl ester method and gas chromatography-mass spectrometry. The results showed that yak yogurt had no significant difference on the contents of protein, fat, lactose and water content (P＞0.05) under refrigeration storage. The total amino acid and flavour amino acid of yak yogurt significant increased after 7 d refrigeration storage (P＜0.05), and the increased rate were 12.96% and 8.51%, respectively; the amino acids score of yak yogurt were 65.36 and 79.18, respectively. The content and kind of saturated fatty acid of yak yogurt had no significant difference after 7 d refrigeration storage (P＞0.05), but the relative content of unsaturated fatty acid of yak yogurt decreased after 7 d refrigeration storage. The kind of volatile substances of yak yoghurt were significantly increased after 7 d refrigeration storage, especially in esters. In summary, it was beneficial to the formation of nutritional composition and volatile substances of yak yogurt under suitable refrigeration storage.