The quality of workpiece is influenced by the surface roughness. However, the assessment of parameters of surface roughness is not researched intensively in the new generation GPS standards system. This paper presents a method to assess parameters of surface roughness. The methodology adopts wavelet analysis to construct the model of surface topography and uses the mallat algorithm to separate roughness profile from surface topography. The assessment results of surface profile are calculated according to the standard ISO 4287:1997. The experimental results show that the method not only avoids simplicity the assessment of parameters, but also decreases the number of productions of mis-acceptance and mis-rejection.