A coarse-grained molecular dynamics simulation model was developed in this study to investigate the friction process occurring between Fe and polytetrafl uoroethylene (PTFE). We investigated the effect of an exteal load on the friction coefficient of Fe-PTFE using the molecular dynamics simulations and experimental methods. The simulation results show that the friction coefficient decreases with the exteal load increasing, which is in a good agreement with the experimental results. The high exteal load could result in a larger contact area between the Fe and PTFE layers, severer springback as a consequence of the deformed PTFE molecules, and faster motion of the PTFE molecules, thereby affecting the friction force and normal force during friction and consequently varying the friction coefficient.