A polyurethane-based nanocomposite with modified hexagonal boron nitride (h-BN) nanoparticle/graphene oxide (GO) was fabricated via effective dispersion of modified h-BN and GO into highly viscous polyurethane prepolymer in the presence of a polymer dispersant in a high energy-density stirred bead mill and subsequently crosslinking with a chain extender. The effects of h-BN and GO particles modified by a saline coupling agent, dispersion and h-BN and/or GO contents on the thermal transport capacity and mechanical properties were investigated, and the Kapitza thermal resistivity at the interface between h-BN nanoparticle or graphene oxide and polyurethane matrix was calculated based on the effect media approximation. The samples were characterized by thermal diffusivity measurement, wear rate analysis, Shore hardness measurement, scanning electron microscopy, infrared spectroscopy and infrared image. The results show that the nanoparticles modified by a saline coupling agent and dispersed with a polymer dispersant in the mill have a good compatibility with polyurethane matrix, thus enhancing the thermal conductivity of the nanocomposite, i.e., (0.671±0.033) W/(m·K), which is increased by 188 %, compared to neat polyurethane, i.e., 0.233 W/(m·K). This is possibly because the incorporation of modified h-BN nanoparticles or graphene oxide into polyurethane matrix can reduce the Kapitza thermal resistivity at their interface. Also, the Shore hardness of the polyurethane-based nanocomposite is 91, which is increased by 4.12%, and the wear rate is 2.03%, which is decreased by 26.63%, respectively, compared to those of neat polyurethane.