Abstract: Laser triangulation method is normally used in the non-contact precision measurement of surface topography due to its simplicity and robustness. In the traditional laser triangulation method, a Gaussian beam is used to scan the measured surface point-by-point. Since data collecting is completed with point scanning, a large number of measurements are needed to obtain the surface topography of the whole surface. Taking non-diffracting light as the incident light of the laser triangulation measurement system, the non-contact precision measurement for surface roughness is fulfilled with a higher speed and it solves the focal depth problem of the Gaussian beam. The evaluation method of the surface roughness based on the grey filtering overcomes the shortages of the existing evaluation methods and is complementary to Gaussian filtering method. The measurement results show that the system measures the surface roughness accurately and the proposed grey evaluation method is effective.