Abstract: The magnetic particle inspection is the first choice for the detection of the defects in the welding seam when the welding position and angle can meet the test standard.But in engineering,actual weld position and shape of the workpiece are often unable to meet the standard requirements,which limit the yoke type magnetic particle testing standard operation.The detection result cannot be of high credibility.With the magnetic yoke end at the head of the characteristics of the magnetic field,the cross weld fillet magnetic particle testing was carried out.The application of yoke detection for the steel corbel fillet weld of the ring crane of nuclear power station was implemented,and certain effect was obtained and the rate of fail-to-detect was reduced.The result can offer a reference for magnetic powder inspection personnel.