Abstract: In order to inspect the post-welding quality of the power battery, this paper proposes a post-weld quality inspection method. This method combines the dynamic threshold and the global threshold, the runs processing and the PCA-SVM classification model for the problems of low contrast, complex background and interference. Firstly, a hybrid threshold algorithm combining dynamic threshold and global threshold is proposed to segment weld seam and defects. Secondly, get a more real edge of the weld seam though use morphology and runs processing to eliminate the interference around the weld seam; Finally, a 7-dimensional feature vector is designed from three aspects:gray features, geometric features and moments. The support vector machine model with principal component analysis is used to inspect pinholes. The results show that the proposed method can achieve good inspection quality.