The feasibility of using Lamb wave group velocity to identify aluminum fatigue damage is analyzed theoretically in this paper.Active Lamb structure health monitoring system is established, and the method of structural damage detection based on Lamb wave group velocity is utilized in the identification process of damage deformation due to metal fatigue.In order to accurately obtain the arrival time of wave packet and Lamb wave group velocity,wave packet decomposition technique is employed to extract excitation wave packet aliasing from the received signal. Moreover,the proposed method is verified by the experiments on the real 7050 aluminum alloy sheet structure,and compared with the shorttime Fourier transform (STFT) method. Experimental results show that the proposed method can accurately obtain the wave packet propagation time and identify the existence of metal fatigue by comparing the group velocity.Also,the proposed method is more effective than the STFT method.