Preparation method of graphene

The invention relates to a preparation method of graphene, which comprises the following steps: evenly mixing a graphene precursor and an amino compound, and performing ball milling for 8-20 hours to obtain evenly-mixed graphene and amino compound mixed powder, wherein the amino compound is used to peel the graphite precursor during ball milling so as to obtain graphene, and the mass ratio of the graphite precursor to the amino compound is 1:(1-10); dispersing the graphene and amino compound mixed powder in solvent to dissolve the amino compound; filtering, and washing the filter cake with the solvent to obtain graphene wet powder; and placing the graphene wet powder in a vacuum drying oven, and drying at 6-120 DEG C for 5-12 hours to obtain graphene dry powder. According to the invention, the graphene is prepared by taking the graphite as the precursor for graphene preparation and using the amino compound to peel the expanded graphite during ball milling; the preparation method has the advantages that the process is simple and the course is easy to control, and can be used for large-scale graphene preparation; and the prepared graphene material has few defects and excellent conductivity.