The paper aims to explore the quantitative relationship between the contact force and the contact speed of the workpiece and the roller-grinding media during the spindle barrel finishing process based on the thinking on studying the correction factor for elasto-plastic contact force of spindle barrel finishing process. The Hertz-Mindlin contact model in EDEM system was used for the simulation. The relational expression between the elastic head-on collision contact force and the contact speed was deduced based on the Hertz contact theory and the Newton’s second law. Then the relational expression between the elasto-plastic contact force and the contact speed was established based on the Thornton’s elasto-plastic hypothesis. The calculated results of the elasto-plastic contact force between the workpiece and the roller-grinding media under different rotating speeds were compared with the results in the experiment. The formula of the elasto-plastic contact force was corrected by quantization of the structural correction factor. Based on the Hertz contact theory, the Newton‘s second law and the Thornton contact mechanics model, the expression of the velocity correction factor was derived with the value between 0.32 and 0.58. Meanwhile, considering the structural displacement correction factor and based on Matlab, the structural displacement factor was obtained between 0.50 and 2.41. The relative error between the corrected calculation results of the elasto-plastic contact force and the experiment results was between 0.122% and 8.901%. The formula for the elasto-plastic contact force between the workpiece and the media is robust in theory and brief in calculation, which can provide a credible help for the design of the barrel finishing process.