The ceramic filter quality detection mainly relies on manual inspection, which has various problems such as low efficiency and poor accuracy. In order to solve these problems, a method based on multi-scale edge fitting was proposed. The idea of multi-scale was introduced to realize the edge detection on multiple scales, and the edge screening strategy was designed to effectively reduce the influence of irregular edge on line fitting. Firstly, an edge detection method based on multi-scale is proposed to accurately extract the edge. Secondly, the edge screening strategy based on piecewise linear fitting is designed to screen out the irregular edge. Thirdly, after screening, the weighted least squares method is used to fit the edge. Fourth, on the basis of the precise linear fitting of the edge, by analyzing the characteristics of defects, the distance difference features are extracted and the defect discrimination rules are constructed to detect the shape defects. Finally, the dimension is calculated by the geometric calculation and compared with the dimension of standard ceramic filter to judge the product quality. The experimental results demonstrate that the proposed method can quickly and accurately detect the dimension and shape defects of the ceramic filter.