Abstract: The edible quality and nutritional quality of yak meat in different ages was determined in this research.The results showed there were major changes in edible quality and nutritional quality as yak get older. The longer the ages of yak, the deeper the meat color, the more plentiful the marble, and the increase the shear force values and muscle fiber diameter with significant differences (p<0.05) , water holding capacity and cooked rate raised, water loss rate dropped;The moisture content decreased gradually, and the fat content and the protein content increased gradually with significant differences (p<0.05) , Ash content had no significant change.It was suggested that there were significant effects of yak quality in different ages, and provided theoretical basis and technical supports of yak grade evaluation methods and standards.