The strengthening mechanism of graphene derivatives in the polymer composites is an interesting issue, which exhibits the excellent mechanical and tribological properties. In this case, the visual observation about the existing state of graphene nanosheets in the polymer composites is much more attractive to explain the intrinsic origin of graphene-strengthening mechanism. At present, the Raman imaging via nondestructive spectroscopic detection is an impactful tool to observe the carbonaceous materials in the graphene nanocomposites. Therefore, the Raman imaging will be applied in this work to detect the existing state of graphene oxide (GO) nanosheets in GO-hybrid polyurethane (PU)/epoxy (EP) interpenetrating polymer network (IPN) with an aim to make clear the GO-strengthening mechanism in GO-hybrid PU/EP IPN. The results obviously indicated the GO nanosheets are chemically bonded between polyurethane and epoxy, which is a key factor to mechanically strengthen GO-hybrid PU/EP IPN by transferring the polymeric stress to the GO nanosheets with high mechanical strength. Besides, the graphitization of GO nanosheets on the tribological surface of GO-hybrid PU/EP IPN is also evidently identified by Raman imaging, which provides a powerful evidence for the improvement of tribological performance in GO-hybrid PU/EP IPN. This work provided the powerful visual Raman imaging proofs for the mechanically/tribologically-strengthening mechanism of GO-hybrid PU/EP IPN, including the appearance of mechanical/tribological quasi-steady state.