High modulus carbon/epoxy composites have been attached more and more importance in the aeronautic field. Because chemical inert of high modulus carbon fiber surface and its poor impregnation for resin, it is essential to improve its polarity in order to enhance the interfacial performances of high modulus carbon/epoxy composites. In this paper, high modulus carbon fiber was treated by ozone oxidation method to modify its surfacial properties. AFM and SEM were used to observe the surface of the carbon fiber, as well as interlaminar shear strength of high modulus carbon fiber/epoxy composite was tested. The impregnation and the interfacial performances of the high modulus carbon/epoxy composites were studied. The results show that after ozone treatment, the surface impregnation of high modulus carbon fiber and the interlaminar shear strength property of high modulus carbon/epoxy composites can be improved obviously.