The effect of vacuum electron irradiation on interlaminar shear strength and mass loss of carbon fiber/
cyanate ester composites was investigated by using space simulation equipment. XPS and SEM were used to characterize the composition and fracture micrograph of composites before and after electron irradiation. The results show thatvacuum electron irradiation of 150 keV has the influence on the surface of carbon fiber/ cyanate ester composites, andwith the increasing of irradiation fluence, the interlaminar shear strength of composites increases first, then decreases.The mass loss goes up quickly first, however, it tends to level off.