Small-scale rough surface scattering represents one of the mostly common scattering mechanisms and yet its Synthetic Aperture Radar(SAR) imaging characteristics have not been well studied. This becomes more critical in millimeter-wave/Terahertz regime as smooth surfaces would become slightly rough under such wavelengths. In this paper, the simplified Small Perturbation approximation Method(SPM) of one-dimensional rough surface scattering based on integral equation and Taylor expansion is presented. Then, the proposed scattering model is served as the theoretical basis for applications such as rough surface spectrum inversion and parameter estimation. This study helps better understanding the phenomenological behaviors of rough surface scattering and lays a foundation for the scattering computation and reconstruction of two-dimensional rough facet.