Abstract: In this paper, graphene layer is formed on the surface of metal substrate (copper substrate) of microchannel radiator by chemical vapor deposition to further enhance the overall heat transfer performance of microchannel. Through the combination of experiment and simulation, the effect of graphene layer on the temperature distribution in the rectangular copper substrate microchannel and the improvement of heat transfer performance by micro ribs under different temperatures and fluid velocity were studied. The results show that the maximum temperature in the microchannel grown with graphene thin layer is reduced by about 7 ℃, and the heat dissipation rate of electronic devices can be increased by 8.1%. The maximum temperature of graphene layer microchannels with micro ribs is reduced by about 2 ℃, and the temperature distribution is more uniform. The numerical simulation results are compared with the experimental results, and the two conclusions are consistent.