Abstract: To ensure the sensitivity of magnetic testing, continuous moving other than discontinuous moving to magnetize workpiece must be adopted in intersecting yoke resultant magnetization. The practical testing has found that the sensitivity of intersectant yoke is related to magnetic mode. Using the continuous moving mode, the defect was also tested effectively. By analysis of magnetic mode of CDX-IY magnetic testing instrument, the sensitivity of intersecting yoke resultant magnetization was discussed. The analysis indicated that resultant field not only formed rotational magnetic field, but also formed one phase magnetic field respectively at 5 ms of turning on and cutting off the magnetic power. The area convered not only by one phase magnetic field but also by resultant field. So, the sensitivity can be ensured by use of discontinuous moving to test.