The Nd-Fe-B magnet was cut by Multi wire Cutting Process of Tolerance Maintaining,the micro-morphology and surface roughness Ra were characterized by SJ-410 roughness meter and JMS-6010LA scanning electron microscope.The results show that with the increase of feed speed and the decrease of linear speed,the indentation depth of diamond grains decreases,and the micro-morphology changes from deep grooves,pits and damage to shallow grooves,shallow pits and crushing,and the material removal mechanism changes from plastic removal to plastic deformation.The roughness Ra decreases with the increase of feed speed and linear speed,and the feed speed and linear speed have opposite effects on the normal load.Plastic deformation and plastic removal play a dominant role in the material removal methods under different process parameters,and the roughness of feed speed 10 mm/h and linear speed 1190 m/min is the lowest and the surface quality is the best.The cutting time is only related to the feed speed,the line bow increases with the feed speed and decreases with the line speed.