Based on the assumption that the abrasive protrusive height obeys Rayleigh distribution,the model of the maximum undeformed cutting depth of a single abrasive particle was established.Considering the influence of variable friction and vibration of machine spindle,taking a single particle as the research object,and the grinding force was divided into grinding deformation force and friction.The vibration correction coefficient of main shaft was introduced,combined with the particle number of per unit area,the total normal force and tangential force of grinding force theoretical model in a unit width was established.The results show that the average relative errors between the theoretical and experimental values of tangential and normal grinding forces are 7.97% and 8.19% separately,and the maximum error does not exceed 15%.