Graphene, which is regarded as a new carbon material, has attracted much attention of scientists. Graphene holds the promise for applications in optoelectronics and microelectronics, owing to many unique physical and chemical properties. The large-scale applications are restricted by controllable synthesis of large-size graphene. In this paper we present the advantages and disadvantages of preparation processes of graphene. The recent advances in the process of metal-catalyzed graphene in terms of lay number control and large area synthesis are discussed. The graphene prepared by metal-catalyzed solid carbon source has large area and high quality and is thin and homogeneous. We review the latest progress in graphene transformation mechanism, point out the limitations of current study and prospect the future development in the graphene transformation mechanism.