In this paper, the specific shear energy in high-speed machining 7050-T7451 from 100m/min to 3000m/min is measured and compared with the theoretical value evaluated by the method proposed by Pawade et al. (2009). The influences of cutting speed, rake angle of cutting tool, and uncut chip thickness are also investigated and discussed. Results show that the specific shear energy decreases with the increase of cutting speed, rake angle, and uncut chip thickness. The higher thermal softening makes the specific shear energy lower.