Abstract: In order to study the material removal mechanism of rail grinding,smoothed particle hydrodynamics(SPH)method is used to simulate the single grain cutting process of rail grinding.In this work,single grains with different geometries,cutting depths and negative rake angles are assumed to cut workpieces.Changes of cutting force,cutting force ratio,stress and deformation of the workpiece are analyzed.Resultsshow that material flow generates burr and chip due to grain pressing,and that the machined surface is superior when the grain is pyramid.In addition,the cutting force increases with increase of cutting depth.Bigger negative rake angle leads to higher cutting force and cutting force ratio,as well as more obvious sawtooth shapd chips.