In this paper, the composition structures of SiC epilayer surface are characterized by high resolution X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectrum. The results of XPS wide scan spectroscopy, infrared glancing reflection absorption spectrum and infrared specular reflection spectroscopy show that the amorphous phase SiCxOy:H is made up of Si-O-Si and Si-CH2-Si polymers. The chemical state structures are composed of Si(CH2)4, SiO(CH2)3, SiO2(CH3)2, SiO3(CH3), Si-Si, dissociative H2O, combined OH，Si-OH, O and O2. The order of the atom core electron binding energy values is determined by chemical state structures and element electronegativity. Compared with the XPS narrow scan spectrum fitting results, the corresponding relation between chemical states and its binding energies is established, and all chemical state binding energies are obtained using the calibration of C 1s binding energy of Si(CH2)4. The result shows that the C 1s and O 1s binding energy values of SiCxO4-x(x=1,2,3) are different from each other, similar as their Si 2p binding energies, of which the C 1s of SiO2(CH3)2 and SiO3(CH3) are respectively close to those of CHm and C—O. The reasonable explanation is presented in terms of chemical state structures, electronegativity and neighbouring site effects.