Surface skewness and kurtosis are two crucial topography property indexes that greatly influence the functional performance of the machined surface. This paper proposes a modified model of stress concentration factor (SCF), which integrates these two surface texture parameters with the well-known standard surface roughness parameters (Arola's model). The relative weight of positive and negative heights of the surface is considered to describe the influence of the shape of the peaks and valleys on the stress concentration of the surface profile for the first time, meanwhile, without losing the effect of the standard surface roughness parameters. The performance of the modified model is studied by comparing it with the other two models involving various aspects of the functional performance of machined surfaces, including fatigue life, wear resistance, fretting crack nucleation, and initiation behaviors, as well as the surface bearing capability. The results indicate that by accounting for the surface skewness and kurtosis parameters, the modified model is more suitable for evaluating the SCF of machined surfaces, appropriately describing the correlation between surface texture and fatigue life and achieving a good prediction of fatigue life compared with the experimental results.