Aiming at the problem that Lamb wave is difficult to quantify the damage of aluminum plate, a short-space two-dimensional Fourier transform method is used to study it. Firstly, the Lamb wave is excited in aluminum plate by air coupled ultrasound and its timespace wave field signals is obtained by linear scanning. Then, the short space two-dimensional Fourier transform is used to obtain the Lamb wave space-wavenumber curve of the scanning area, and the location, length and depth of the damage are obtained. Finally, the depth of damage is deduced from the phase velocity frequency-thickness product curve. The results show that the proposed method can simultaneously evaluate the plate thickness of the scanning area and the location, length and depth of the damage. Among them, the maximum quantitative error of plate thickness is 5. 50%, and the maximum quantitative error of damage length and depth is 6. 00% and 6. 67%.