Lamb waves received great attention in structural health monitoring (SHM), but it is complicated by the multi-mode character and the dispersion effect, which impacts the damage positioning and high-resolution imaging. Warped frequency transform(WFT) can warp the frequency axis by setting up a reasonable warped map. Warped frequency transform based on the group velocity dispersion curves of Lamb waves can be employed to process Lamb waves. Based on this direct dispersion compensation idea, WFT is adopted here to process the measured signals to suppress dispersion. A new method of high-resolution damage imaging is proposed based on WFT, and the propagation of Lamb waves in damaged aluminum pate is simulated by finite element software ABAQUS. Results show that WFT can effectively compress dispersed wave-packets, and high-resolution damage imaging can be obtained by the proposed method.