Abstract: Improving the performance of polytetrafluoroethylene (PTFE) becomes a popular research area, which plays an important role on the actual application in the aerospace, machinery, chemical industry field, and so on. The common enhancement methods for polymer are filling fibers, nanosheets and micro-nano particles. However, the reinforced mechanism has not been fully understood, especially under an atomic level due to experimental measurement limitation. In this study, we employed a molecular dynamics (MD) simulation to study the tribological properties of PTFE reinforced by modified graphene with excellent mechanical strength in order to explore the reinforced mechanism from a molecular view. Firstly, graphene oxidation (GO), as a reinforced filler, was grafted by three different silane coupling agents, KH550, KH560 and KH570, to improve the interfacial compatibility with PTFE matrix, respectively. The calculation results indicated that PTFE composites filled by KH560-GO had the highest Young's modulus and shear modulus, which was increased by 205% and 116%, respectively. Then, the frictional model of PTFE composites sliding against copper based on the contact of ultrasonic motors was built and the tribological properties was evaluated. The simulated results showed that the friction coefficient of PTFE was increased by 39.6% after filling the KH560-GO. The shear deformation was also greatly reduced after filling GO modified by silane coupling agents. Besides, the polyimide (PI) with high rigidity was selected to modify GO to further improve the mechanical strength of PTFE. The ungrafted GO and single PI molecular were also filled in the PTFE matrix to compare the effect of modification. It was obviously found that the PI grafted GO had the higher Young’s modulus and shear modulus than that just filling GO blended with single PI molecular, increased by 71.2% and 56.9%, respectively. Finally, the reinforcement mechanism was systematically analyzed by observing the dynamic evolution of whole shear process and extracting the variation information of the interface characteristics. Visually, silane coupling agents and PI molecular had the favorable compatibility with PTFE molecular which resulted in the strong interfacial interaction due to mechanical interlocking effect. The PI chains were grafted almost vertically on the surface of GO. Thus, the silane coupling agents and PI grafted GO had the higher interaction potential energy with PTFE than single graphene or PI blends. More PTFE molecular were adsorbed on the surface of modified GO under the van der waals, electrostatic adsorption and other forces, which contributed to high mechanical strength and shear modulus. Under the same shear condition, silane coupling agents and PI modified GO reinforced PTFE had a smaller shear deformation than pure PTFE and graphene nanosheets (GNS) reinforced PTFE. After further analysis on the frictional interface, it can be easily found that the temperature, velocity, relative concentration variation and interaction energy with counterpart was different after filling different GO. On the frictional interface, pure PTFE had higher atomic velocity, relative concentration and interaction energy because of strong intermolecular forces with copper atoms. After reinforced with modified GO, more PTFE chains were adsorbed on the surface of GO, which reduced the interaction with counterpart. It was consistent with friction reduction, wear resistance and mechanical performance improvement. This study revealed the enhancement mechanism of modified GO on the PTFE using MD simulations from an atomic level, which had a helpful guidance for designing other polymer composites reinforced by different fillers.