Surface properties of carbon fiber/cyanate ester (CFCE) were investigated after exposure to hyperthermal atomic oxygen. SEM and XPS were used to characterize the chemical and physical changes of the surface of the material. The results indicated that the erosion yield of CFCE is (2.20±0.36)×10^-24 cm³/atoms. The relative atomic concentration of C and O, increase and decrease respectively. The surface got rougher with increasing AO fluencies, and as carbon fiber exposed to hyperthermal atomic oxygen, the surface tended to shape cavities, and link ravines finally. The scattering tests show that the productions of CFCE to hyperthermal atomic oxygen are CO、CO₂、H₂O、OH and CH₃.