Abstract: ZnO whisker , which possesses stereoscopic st ructure , was int roduced into M40J / bisphenol-A dicyanate(BADCy) composite to improve it s ILSS1 The reaction mechanisms of BADCy blend with epoxy resin E51 and ZnOwhisker were studied by FTIR spect roscopy1 It was found that ZnO whisker serves as a catalyst of polycyclot rimerize reaction of BADCy , and post-cure temperature of BADCy/ E51 blend system was descended from 200 ℃ to180 ℃. The result s indicated that when 10 % ZnO whisker t reated by KH560 is int roduced , the ILSS and flexuralmodulus of M40J / BADCy composite could improve from 77.6 MPa and 178.9 GPa to 91.2 MPa and 207.4 GPa respectively , while with the unt reated ZnO whisker they are improved only slightly. The SEM analysis of f racture surfaces of broken specimens indicates that the ILSS and flexural modulus of M40J / BADCy composite were improvedby means of the“nail”of ZnO whisker in the laminar of M40J / BADCy composite.