Welding technique has been widely used in various fields of modern engineering. As the impact of various parameters during welding process,there will be some cracks,pores,slags,and no fusions defects in welding structures inevitably. In order to ensure the welding product quality, all welding structure should be inspected and evaluated effectively. The yoke-magnetization is usually applied in MFL-testing of welds. In this paper, we focus on the yoke-magnetization testing for a fillet weld and analyze the ch...