▎ 摘　　要

NOVELTY - Preparation of millimeter-sized single-layer monocrystalline graphene, involves placing the copper foil into the quartz tube furnace, and annealing at 1070 degrees C for 2-5 hours, under argon atmosphere of 300 sccm, introducing 0.5 sccm methane and 50 sccm hydrogen for 2 hours, maintaining the temperature of the tube furnace to 1070 degrees C, opening the tube furnace, quickly cooling down and passing 300 sccm argon and 4 sccm hydrogen, reducing furnace temperature to room temperature and growing millimeter-sized single-layer monocrystalline graphene. USE - Preparation of millimeter-sized single-layer monocrystalline graphene (claimed). ADVANTAGE - The preparation process is simple, and large-scale production is achieved.