Wear is the most frequently surface failure of the materials, and roughness is the most commonly used parameter to describe the characteristics of the worn surface numerically. Laser scanning confocal microscopy (LSCM) was used to get the image of wron surface topography by adjusting the objective lens and measuring field of view and filter parameters, the accurate numerical description of the three-dimensional (3D) worn surface was obtained at the same time. For commonly roughness value between 0.5 and 2.0 μm, the 20× lens is the best choice, while for the larger or smaller roughness value, 10× and 50× lens should be used, respectively. For regular worn surface, the accurate roughness value can be obtained within 1 to 3 combined optical field, while for the irregular one, the combined number of optical field should be 3 to 5 or more. Based on this method, the worn surface topography of a Cr5 cold roll was well analyzed in different wear patterns.