Abstract: Yak meat were placed under 2℃ and 10℃ respectively after hot-boning and vacuum packing.pH, shear force, cooking loss and meat color were measured at 1, 2, 3, 4, 6, 12, 18d during postmortem aging, to study the effect of time and temperature on quality of yak meat.Results showed that from 1d to 12d, pH of meat under 2℃ kept rising, while meat under 10℃ changed little, then both of them decreased during 12¹8d.Yak meat became tender with extend of post aging time, but shear force of 10℃ significantly lower than meat of 4℃.L*, a*, b*, C*, h had overall risong trend during post aging.Generally concluded that, yak meat from hot-boning and vacuum packing reached end point placed under 2℃ after 18 days' post aging, and it needed shorter time placed under 10℃.