Abstract: An individual section of the arc welding pool image has a close relationship with the ultimate weld seam formation. An analysis on the fractal dimension and multi-scale fractal feature of the slag and the weld pool part is performed,and the definitions of graphical fractal dimension and multi-scale fractal feature are also elaborated. An image segmentation method using both single fractal dimension algorithm and multi-scale fractal feature-based algorithm is introduced,which has been applied in the processing of arc welding images. Experiments show that the tail of the weld pool and the slag are effectively divided in the way mentioned above,which is superior to the segmentation method based on Sobel operator and single fractal dimension algorithm.