According to the spatial distribution pattern of melt pool size features, a prediction method of melt pool width based on edge iterative model was proposed. In order to obtain accurate melt pool width, mathematical morphological method was used to denoise the melt pool image and coarse segmentation was conducted on the melt pool image by manual thresholding method. The Canny algorithm was then employed to extract the melt pool edge. Finally, the edge iterative model was used for edge iteration and the melt pool width after fine segmentation was obtained. Comparison experiment results show that this algorithm has good accuracy and robustness, and it is simple and efficient.