The invention belongs to the technical field of inorganic compounds, and particularly, relates to a method for directly preparing graphene by taking CBr4 as a source material and using methods such as molecular-beam epitaxy (MBE) or chemical vapor deposition (CVD). A method for preparing graphene comprises the following steps: selecting a proper material as a substrate; directly depositing a catalyst and CBr4 on a surface of the substrate; and performing annealing treatment on the sample obtained through deposition. Compared with other technologies, an innovative point of the method in the invention is that the catalyst and CBr4 source can be quantitatively and controllably deposited on any substrate, and the catalyst and CBr4 source react on the surface of the substrate to form the graphene, so that the dependence of the graphene growth on a substrate material can be reduced to a great extent, and different substrate materials can be selected according to different application backgrounds.