Abstract: Beef knuckle contains less amount of fat, which tastes dry and hard after being pan fried. In order to increase the richness of the juice of the steak made of that, promoting the formation of a soft and tender taste as well, this experiment studied the effect of injection of walnut oil emulsion under high-pressure and low-temperature on steak quality. In this experiment, beef knuckle steak added with walnut oil emulsion had been successfully prepared through injection under high-pressure and low-temperature followed vacuum tumbling technology, and the influence of emulsions with different transglutaminase (TGase) content (0%, 0.3%, 0.6%, 0.9%, 1.2%) on the emulsion bonding capacity of steak and the influence of emulsion with different walnut oil content (20%, 30%, 40%, 50%) on the physicochemical indexes and quality indexes of steak were studied. The bonding capacity of steak adding emulsion increased with rising TGase contents in emulsions, and stabilized after TGase contents reached 0.9%. Injection walnut oil emulsions into steak increased its moisture contents by 1.44%~2.31%, and decreased pH value by 0.17~0.08, increased then decreased L^* value, decreased a^* value and b^* value. The shear force of steak were reduced by 26.62%~65.33%, the yield were increased by 3.43%~11.43%, the hardness and chewiness of steak were reduced by 15.44%~77.06% and 26.56%~77.52%, respectively. Sensory evaluation experiments showed that the injection of emulsion improved the softness and juiciness of steak products, yet had little effect on the flavor and tastes. Through the comparison between influence of emulsions contain different amount of TGase and walnut oil on the process performances, physicochemical properties and quality indicators of steak, the emulsion with TGase content of 0.9% and walnut oil content of 40% was most suitable for production practice.