In this paper, a zero-mean, band-limited Fractal function is introduced to simulate rough surface profile. According to the Kirchoff Theory, the surface roughness measurement is simulated with the help of the fast Fourier Transformation technology. The relationship between the surface parameters and the reflected light intensity distribution is obtained. In order to quantify rough surfaces, some criteria are proposed. Numerical results show that these criteria have a strong correlation with the root mean square of the surface height variation and they can be used for surface roughness measurement and classification.