Abstract: Running-in wear test for materials of piston ring against cylinder liner was conducted on a pin-on-disc tester. The surface topography was observed and analyzed by an optical microscope. Low frequency feature parameter and high frequency feature parameter of worn surface based on statistical feature were extracted by using wavelet analysis and singular value decomposition. It was shown that low frequency feature parameter and high frequency feature parameter revealed the topography feature of running-in surface. Low frequency feature parameters reflected contact area of the running-in surface, the larger low frequency feature parameters, the larger contact area. High frequency feature parameters reflected roughness of the running-in surface, the larger high frequency feature parameters the smaller roughness. Therefore low frequency feature parameter and high frequency feature parameter can be used as the feature parameter for the running-in surface evaluation.