Aiming to the quality control and service performance evaluation of metal plates, a dynamic time warping of guided waves method based on shape context is proposed to quantify the micro-damage in aluminum plates. Using the Lamb wave signal of the intact metal plate as the baseline, the dynamic time warping(DWT) algorithm is applied to match the damage signal to the baseline so as to determine the optimal warping path. The shape context(SC) contour recognition method is introduced to statistically analyze the local waveform information of Lamb waves. The shape distance of waveform is used to replace the traditional Euclidean distance, and the ill alignment problem in the DTW similarity matching is solved. Finally, the SC-DTW matching distance between damaged signal and baseline is used as a quantitative index to describe the damage degree. The finite element simulation model of random closed cracks and bending test of aluminum plates are used to verify the proposed method. The results show that the damage quantification index based on the Lamb wave SC-DTW has high sensitivity and good quantitative characterization ability for the early crack of the aluminum plate. This method does not need to identify the wave packet, and does not need to deal with the feature extraction, which has the advantages of simplicity, high efficiency and strong anti-noise ability, and has good practicability and popularization value in the quality control and service performance evaluation of metal plates.