<p>The edge radius of the cutting tool play a significant role in the milling process. Cutting edge passivation can enhance the cutting performance and service life of tools. This paper proposes a novel cutting edge passivation method for milling cutters using magnetic field assisted shear thickening fluid polishing. The microscopic material removal mechanism of this polishing method is introduced, and the polishing fluid is prepared and its rheological properties are tested and analyzed. The flow fields of milling cutter surface under different process parameters are obtained by finite element simulation. The influence of process parameters such as polishing disc speed, tool speed, and magnetic induction intensity on passivation radius and surface roughness are investigated by polishing experiments.The comparison between simulation and experimental results shows that increasing polishing disc speed is beneficial for enhancing the cutting edge radius and surface quality. The cutting edge radius increases with the increasing tool speed, while the larger the cutting edge radius is achieved with higher tool speed. The edge radius and surface roughness improvement rate are positively correlated with the magnetic induction intensity at low magnetic induction intensity, and the passivation radius of the tool is reduced under high magnetic field intensity. Under a weak magnetic field strength (60mT), cutting tools can achieve a larger passivation radius. The edge passivating radius is consistent with the material removal rate obtained by the flow field simulation. The research results provide reference and basis for cutting edge passivation of milling tool by magnetic-field assisted shear thickening polishing.</p>