To improve the heat transfer characteristics of lubricant, graphene-based lubricants were prepared by adding graphene particles, due to its advantages of excellent thermal conductivity and two-dimensional sheet structure. In the present study, its physical properties were measured. A flow heat transfer experiment platform was built to study the flow and heat transfer characteristics of the graphene lubricating oil in a horizontal circular tube. The results show that the graphene lubricant prepared using a two-step approach had good stability, and the dispersibility was good without the agglomeration phenomenon, according to measurements undertaken using an electron microscope and centrifuge. The thermal conductivity and viscosity of graphene lubricant increased with the increase of the graphene concentration, and the thermal conductivity of graphene lubricant with the same concentration decreased with the increase of temperature. When the concentration was equal, the convective heat transfer Nusselt number (Nu) of graphene lubricant increased with the increase of Reynolds number (Re). When Re was equal, the convective heat transfer Nu increased with the increase of graphene particle concentration, and the maximum Nu increased by 40%.