Abstract: In order to research the electromagnetic characteristics of the magnetic control arc welding seam tracking sensors, the harmonic magnetic field of sensor is analyzed with ANSYS software:when the coil circle number, air gap length, core magnetic conductance factors change respectively, the magnetic control arc welding seam tracking sensors magnetic maps and magnetic field vector diagram are obtained.The influence law of the main parameters of arc sensor on the magnetic field distribution and the size of the magnetic induction is analyzed, and is compared with the actual magnetic induction intensity measured by gauss plan.The results show that analysis results of using the finite element method for magnetic control arc sensor electromagnetic properties and test results are coincide.It provides theoretical guidance for magnetic control arc welding seam tracking technology.