Abstract: The effect of low-frequency longitudinal magnetic field on microstructure and mechanical properties of deposited metal of submerged arc hardfacing was studied by analysing the weld formation,hardness,wear-resisting property and microstructure of the deposited metal.The action mechanism of low-frequency magnetic field to improve the microstructure of the deposited metal and the wear-resisting property of hardfacing layer was discussed.The experiments show that low-frequency longitudinal magnetic field makes the welding pool width increase,welding penetration slightly reduce,the crystal grain be refined from 25.6 μm to 10.6 μm,the hardness increase from 50.5 HRC to 55.0 HRC and the wear rate decrease from 0.035 g to 0.015 g.So the low-frequency longitudinal magnetic field can refine the crystal grain effectively and improve hardness and wear-resisting property of hardfacing layer.