Abstract: The weak interfacial strength is the important factor influencing the mechanical performance of aramid/epoxy composites. In this paper, the ultrasonic technique is applied to increase the impregnation of the resin during resin impregnating aramid fiber, which improves the interfacial properties of the composites. The optimal parameter of treatment is studied, emphasizing on the research of the effect of the ultrasonic treatment on the mechanical performance of composites.