Abstract: The CFRP and GFRP laminates with a crack on a single side are loaded under tensile impact by the apparatus of Hopkinson bar.The curves of the load P(t) loaded on the specimens and the displacement δ(t) of the specimens were acquired according to the one-dimensional stress wave theory. The curves of dynamic stress intensity factor K_Ⅰ (t) were set up according to the fracture toughness measuring theory and the stress changing σ(t) with time in the specimens. With the compliance changing rate method, the crack initiation time and the dynamic fracture toughness of CFRP and GFRP laminates were obtained at two kinds of strain rates separately. The experiment results show that the fracture toughness of CFRP and GFRP laminates increased with loading rates increasing.