The researchers used POSS as the medium to connect graphene oxide and carbon fiber, and studied the effect of synergistic modification of two nanomaterials on the interface properties of carbon fiber/epoxy resin composites. After grafting polyhedral oligosasiloxane (POSS) and graphene oxide (GO) layer by layer on the surface of carbon fiber, the composite material is prepared by using it to strengthen epoxy resin (CF/EP). The effects of POSS and GO composite grafted carbon fiber on the mechanical properties of CF/EP composites were investigated by scanning electron microscopy, contact Angle testing and X-ray photoelectron spectroscopy. The results show that POSS and GO can significantly increase the surface activity and specific surface area of carbon fiber, and improve the infiltration, reactivity and mechanical meshing between resin and carbon fiber, so as to improve the interface properties and mechanical strength of the composite. Compared with the unmodified carbon fiber composites, the interlayer shear strength (ILSS) and bending strength of the modified carbon fiber composites grafted by POSS/GO composites are increased by 98.3% and 95.7%.