Abstract: Yak meat as the research material, shear force as review indicator, tenderizing effects of the papain were researched. Three parameters including enzyme liquid pH, enzyme concentration and tenderizing time were optimized using response surface central rotating composite design for process optimization. Finally, the mathematical model of each parameter was set up and response values were analysed. The result showed that the influencing factors on shear force of yak meat were concentration of enzyme, pH of enzyme liquid and tenderizing time in order. Optimum parameters were pH5.1, concentration of enzyme 9.63mg/L and tenderizing time 14.5h. Under this condition, the shear force was 4.76kg·f and reduced 2.19kg·f compared with the yak meat which was not tenderized. Electron microscope scanning results showed that the muscle fiber structure of yak meat which was treated by papain had obvious fracture trace compared with the contrast test.