Abstract: The interlayer properties of carbon fiber reinforced resin matrix composites are always the weakness of composites. A composite film was designed and fabricated using graphene oxide (GO) and carbon nanotubes (CNT), which exhibited good permeability and resin wettability. A hybrid carbon fiber/epoxy (CF/EP) composite was prepared using the composite GO-CNT film by interlayer toughening method. The interlaminar toughness of the GO-CNT-CF/EP composites was investigated by open type interlaminar fracture toughness (G_IC) and slip type interlaminar fracture toughness (G_IIC). The interlayer toughening effect and toughening mechanism of the GO-CNT composite film on the GO-CN-CF/EP composites were analyzed based on the damage micro-morphology and damage/destruction characteristics of the composites. The results show that the composite GO-CNT film prepared with a mass ratio of GO to CNT of 3∶7 has good film-forming processability and resin wettability.The contact angle between EP and GO-CNT composite film is much lower than that between EP and pure GO film. Moreover, GO and oxygen-containing groups such as hydroxyl, carboxyl, and epoxy group in CNT increase their physical affinity and chemical interaction with EP, which is conducive to the toughening of GO-CNT/EP microzone structure between layers of composite materials. The GO-CNT composite film has no enhancement effect on the G_IC of the composite. The G_IC value of the GO-CNT-CF/EP composite even dropped slightly compared to the CF/EP composites. However, the GO-CNT composite film has a good effect on improving the G_IIC of the GO-CNT-CF/EP composite. The G_IIC of the composite increased from 1855 J/m² for the CF/EP composite to 2720 J/m² for the GO-CNT-CF/EP composite, which has an increase of 47%. This is attributed to the interpenetrating and overlapping network structure formed between the GO-CNT composite film and the resin, which inhibits the propagation of interlayer microcracks caused by slip-type loading. The glass transition temperature of GO-CNT/EP composites is similar to that of CF/EP composites.