Abstract: The tribology behavior of nano ZnO/nitrile-butadiene rubber (NBR) composites was studied by molecular simulation. The investigation was conducted using molecular simulation to examine the radius of gyration, relative concentration of atom and shear behavior of nano ZnO/NBR composites. The microscopic mechanism of tribology behavior of nano ZnO/NBR composites was discussed. The results show that compared with the pure NBR, the nano ZnO/NBR composites owns a smaller radius of gyration and the flexibility of rubber molecular chain is decreased. Compared with the nano ZnO/NBR composites, the pure NBR owns a higher relative concentration of atom at the frictional interface. The peak value of relative concentration of atom at the top and bottom friction surface of pure NBR is 6.4% and 4.3% greater than that of nano ZnO/NBR composites, respectively. The rigidity of molecular chain in nano ZnO/NBR composites is enhanced and the energy dissipation is decreased. The improved tribology property is achieved in the nano ZnO/NBR composites.