The object of this work is to investigate the effect of EB irradiation on carbon fiber surface. The laser Raman spectroscopy, X ray photoelectron spectroscopy (XPS),atomic force microscopy (AFM) and X ray diffraction were used to observe the surface changes including an enhancement in oxygen and nitrogen containing groups,smooth degree of carbon fiber surface and in size of graphite crystal layers. It showed that polar groups on carbon —fiber surface were influenced by the active species creacted in the media during EB irradiation. The self—quenching reaction or disengage reaction took place in activated groups. The group C=O was increased in the former reaction, on the other hand, the group C—O in the latter reaction. The crystal structure of the bulk carbon fiber was not effected by EB irradiation.