Abstract: The dynamic mechanical properties of carbon fiber and aramid fiber reinforced epoxy resin plain weave composites were tested using high speed tensile testing machines and Hopkinson pull rod devices, respectively. The results show that during the stretching process, carbon fiber and aramid fiber exhibited brittle fracture characteristic, the elastic modulus of both materials was almost unaffected by strain rate. The tensile strength increased with the increase of strain rate and was linearly related to the logarithm of strain rate.