The dynamic evolution law of brass surface in brass–steel tribopair during wear process is studied byusing monofractal and multifractal methods. Wear tests are performed on a ring-on-disc tribometerunder mixed lubrication. The profile of brass surface is measured by the reposition-measurementapparatus. Both the maximum peak-to-valley height Rt and the width of multifractal spectrumΔαdecrease in running-in wear stage, maintain at a small value in steady wear stage, and increase rapidly insevere wear stage. While the evolution of fractal dimension is opposite to that of Rt andΔα. The resultsare instructive to wear state identification.