The two-scale Model (TSM) is broadly employed for studying EM scattering from rough sea surface due to its advantage of simple and practical. However, it suffers from a drawback in the prediction of microwave scattering from sea surface. That is the TSM cannot provide accurate predictions for hh polarized scattering coefficients. To overcome this problem, a modified TSM (MTSM) is proposed in this paper. Through analysing the validity conditions of the KA (Kirchhoff approximation) and SPM (small perturbation method), the concept of ‘transition spectral region’ is proposed for the first time. In this region, both the validity conditions of the KA and SPM are satisfied, indicating both the specular scattering and Bragg scattering contributed to the scattered energy in this region. Therefore, in the MTSM, two cut-off parameters are used to divide sea surface roughness into ‘specular scattering region’ and ‘Bragg scattering region’. Additionally, in the MTSM, the KA-SP rather than the commonly used KA-GO is employed for simulating the specular scattering component. Numerical simulations confirm that the MTSM performs better than the TSM and the SSA-1, especially in the prediction of hh polarized scattering coefficient.