Abstract: Currently, when using a single magnetization direction magnetic particle testing machine for testing, sensitivity verification is generally carried out using the linear defect groove and circular defect groove of the current magnetic particle testing specimen. The authors referred to relevant national and international standards, combined with practical experience in magnetic particle testing work, and through analysis, found that: when using current test pieces to verify the detection sensitivity in a planar detection area, some angles deviating from the direction of magnetic field magnetization were facing upwards, and the detection sensitivity verification sometimes failed; In practical work, it was difficult to use the current defect slot of the test piece to calculate the angle range for effective detection of defects in one magnetization and calculate the minimum number of magnetization times, so it was difficult to use the current defect slot of the test piece to avoid missed detections; Multi angle defect groove magnetic particle testing specimens can solve the problems of insufficient sensitivity verification effectiveness and difficulty in calculating the minimum magnetization number in actual testing work for all current specimens.