Abstract: Yak bone was raw material in this study, studied influence of optimization of concentrated bone soup of collagen protein content by Central composite design. It was concluded that the maximum response value corresponding to the optimal conditions which the bone block size was 3cm, liquid ratio was 3∶20, and boiling time was 4h. Under the condition, the bone soup decocted best, volatile substances were found in bone soup rich in volatile components of 74 kinds by GC/MS testing. The characteristic aroma was from aldehydes, esters, alcohols, ketones and heterocyclic compounds, including 2, 4-sorbaldehyde, heptyl-2-hepenal, heptyl-2, 4-decadienal, heptyl-2-dodecenal, heptyl-2-hexenal, benzothiazole, 4-propenyl-2-methoxyphenol and so on which had contributed to concentrated bone soup characteristic flavour. In addition, contained many fresh bone that contains the characteristic substances, also produced a lot of material what the fresh bone did not contain. And it also produced 2, 5-dimethylpyrazine, 2, 3-dimethylpyrazine, β-sesquiphellandrene, 2, 3-Octanedione, 1-octene-3-alcohol and so on.