The invention discloses a graphene preparation method based on soft-hard mold plates in the field of nano-carbon material preparation. The method comprises the following step: by taking a surfactant, namely cetyl trimethyl ammonium bromide (CTAB) as a structure-directing agent, taking tetraethoxysilane (TMOS) as a silicon source, and taking oil-soluble organic small-molecular pyrene as a carbon precursor, synthesizing an SiO2/CTAB/pyrene composite material under an acidic system. According to the graphene preparation method disclosed by the invention, the surfactant CTAB is taken as a soft mold plate and a layered silicon dioxide material is taken as a hard mold plate synchronously in a preparation process so as to ensure that the agglomeration of graphene can be effectively avoided; and moreover, the graphene preparation method is easy to operate, simple in process and good in reproducibility, and a new referential thought for preparing high-quality dielectric substrate graphene and graphene solutions can be provided.