Abstract: In order to improve the calculation accuracy of air-gap magnetic field and retarder brake torque,vector magnetic method is applied to eddy current field finite element analysis in permanent magnet retarder,and non-linear permeability of rotor and the weakening effect in magnetic field generated by eddy current magnetic field are considered.By using finite element simulation software and hybrid automatic mesh generation techniques,a numerical solution of permanent magnet retarder electromagnetic fields is obtained.Experiments show that the discrepancy of flux densities in the air gap between measurement and calculation is below 5%,and the calculated braking torque is fairly in good agreement with the measured one.