Abstract: The distributions of surface height, surface asperity and valley number of various sedan steel plates were analyzed by correlating the surface profile features with the tribological behavior. As the results, these distributions are correlative with the lubrication performance and contact behavior of the surfaces. A kind of non linear curve fit method based on Weibull probability density function was adopted for the analysis of the distributions because of their non Gauss distribution feature. Some important parameters with explicit physical meanings are established by the curve fit method. Thus it is feasible to express the characteristic distributions of the surface profiles of various sedan steel plates using lessened parameters as alternatives of the probability density functions.