The invention relates to a graphene preparation method. The method comprises the following steps: 1, uniformly mixing an adsorption medium with graphite in proportion, and placing the obtained mixture in a rolling machine; 2, starting the rolling machine, uniformly mixing the rolled mixture, and continuously repeatedly rolling the mixture for several hours to realize full contact of the graphite and adsorption medium mixture and make the graphite peeled layer by layer and adhered to the surface of the adsorption medium. Expanded graphite is mixed with a halogen salt by mainly using the viscose characteristic of a halogen salt formed by halogen and metal, the obtained mixture is continuously rolled and broken in the rolling machine. The graphite is adhered to the surface of the halogen salt layer by layer with the continuous rolling of the graphite and the halogen salt, so the mutual adsorption degree is enhanced. The layer-by-layer peeling and breaking effects are also reached.