To enhance interfacial adhesion between matrix polymer and Kevalr 49 fiber for composites, amino groups(-NH2) have been incorporated into Kevlar 49 fiber surface by bromination f311owe6 by amination. The number of amino groups per 100A2 fiber surface remarkably increased with increasing reaction time and temperature, and the concentration of N-bromosuccinimide(NBS) , ethylene diamine(EDA) and sodium amide. Tensile strength loss of the fiber on bromination was negligible, however, the significant strength loss of the fiber was observed in case of the high -NH2 content produced by severe reaction condition of amination, in which reaction may have occurred beneath the surface artier disruption of the structure. Pretreating the fiber with N, N-dimethylacetamide (DMAc) before bromination was effective to enhance the number of amino Voups. The optimum concentration of amination has been established to reduce down to about 10% of tensile strength loss. Grail copolymers of nylon 66 onto aminated Kevlar 49 fiber surface were prepared by the polycondensation reaction of amino Voup and acid chloride by dipping the aminated fiber into DMAc solution of adipoyl chloride and then into DMAc solution of hexamethylene diamine consecutively. The grafting percentage increased with increasing number of repeating reactions and reaction time.