Abstract: Based on excellent physical property of Polyetherimide(PEI) and high specific surface area and high porosity of nanofibers, PEI nanofiber membranes with different thickness being bubble-electrospun to be used to improve the interfacial toughness of the carbon fiber/epoxy composites. It is found that when the thickness of membrane is 0. 058 ± 0. 007 mm, the value of G_IC of DCB sample increases by 114. 55% in contrast to that of the untoughened, which is attributed to the nail-anchorage action of the PEI micro-beads at the interface.