Abstract: The dynamic mechanical temperature spectrums of epoxy resin and the fiber-glass/epoxy composites have been studied under tensile-tensile stress in the range from 150℃ to 200℃.The effect of filler on the relaxation behaviour of epoxy matrix has been analyzed.It was oberserved that there is an additional peak (a'-peak) at the higher temperature side of the glass transtition peak (a-peak) on the damping-temperature curves of composites The new a'-peak was of obvious asymmetrical characters,and affected by the. contents and the surface treatments of fiber,whieh was considered as the effect of interface.The activation energy of a and a' transtitions have been measured by experiments.The relatpve height index ψ, was introduced for evaluating the contributions of interface.