▎ 摘　　要

NOVELTY - Graphene preparation involves putting substrate in a closed cavity cooled by circulating water at 100 degrees C. The carrier gas is ventilated and substrate is heated. The gas containing carbon source is ventilated continuously for 5 seconds to 30 minutes, where the graphene is generated on surface of the substrate after cooling the substrate. USE - Method for preparing graphene (claimed). ADVANTAGE - The method prepares the graphene with good uniformity, large area, less flaws, excellent electricity conductivity and good mechanical characteristics. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a device for preparing grapheme, which comprises an air inlet and an air outlet on closed cavity, where the air inlet is connected with containers of the carrier gas.