Abstract: Carbon fiber surface properties were systematically studied by means of measuring specific surface, contact angle, wettability surface energy and surface group.Specific surface measured bY dynamic absorption method, increased with the oxidation treatment time, rose from carbon fibers etched bY acid.The most probable pore distribution of carbon fibers tested is in the scope 10-12Å.The changes of surface energy were measured by contact goniometer and increased with oxidation treatment time too.There were the dispersion and polar components of surface energy in which the polar components increased obviously and the dispersion tomponents decreased slightly.The contact angles with respect to epoxy resin or water decreaseed witn the oxidation treated time.The treatment modified the wettabilities of treated fibers toward better ones.Then, changes of wetting velocity of carbon fibers were measured by microbalance.The wetting velocity in water increased about 3 times of ter the oxidattion treament of carbon fibers, which further verified that the wettabilites became better by oxidation treatment.