▎ 摘　　要

NOVELTY - Preparing graphene, comprises (i) adding a metal catalyst into a reactor, heating, and preserving heat; (ii) maintaining the constant temperature of the metal catalyst, sealing the reactor under vacuum state, and then closing a vacuum pump, and maintaining vacuum state in the reactor; (iii) introducing carbon source gas and reducing gas into the reactor to carry out variable pressure chemical gas phase deposition; and (iv) turning off the carbon source gas once the pressure in the reactor is increased to atmospheric pressure, and maintaining flow rate of reducing gas and inert gas. USE - The method is useful for preparing graphene (claimed). ADVANTAGE - The method changes the rate pressure so as to control the morphology and the number of layers of graphene. DETAILED DESCRIPTION - Preparing graphene, comprises (i) adding a metal catalyst into a reactor, heating at 1000-1050 degrees C, and preserving heat; (ii) maintaining the constant temperature of the metal catalyst, sealing the reactor under vacuum state, and then closing a vacuum pump, and maintaining vacuum state in the reactor; (iii) introducing carbon source gas and reducing gas into the reactor to carry out variable pressure chemical gas phase deposition; and (iv) turning off the carbon source gas once the pressure in the reactor is increased to atmospheric pressure, and maintaining the flow rate of reducing gas and inert gas, while the reactor is sealed, and exposed to outer environment, and obtaining the final product.