Abstract: In order to establish an evaluating standard of self-repairing properties for nano-copper additives, a standard method for measuring the mass increment of frictional pair after tribological tests was proposed. The method proved to be effective by tribological tests on a commercial nano-Cu antiwear and self-repairing additive. The tribological tests were performed on a MRH-3 block-on-ring test machine. Test conditions using various load, rotation rate, test duration, as well as volume fraction of additives were investigated. Based on the experimental data, the test method and appropriate conditions for evaluating self-repairing properties of lubricating additives were established. The repeatability and reproducibility of the standard tests were also evaluated. The morphologies and elements composition of the worn surfaces on test blocks were analyzed by scanning electron microscope and X-ray energy dispersive spectroscopy. The results indicate that nano-Cu additive exhibit excellent antiwear and self-repairing properties; and the feasibility of test method and conditions proposed in.