The invention provides a preparation method of a graphene aerogel, a Fe3O4/graphene aerogel and a preparation method of the Fe3O4/graphene aerogel, and belongs to the technical field of graphene aerogels. The preparation method of the graphene aerogel comprises the steps that an annealed porous silicon dioxide framework is placed at 1,100-1,300 DEG C, through a chemical vapor deposition method, graphene grows, and pretreated gel is obtained. The porous silicon dioxide framework in the pretreated gel is removed to obtain the graphene aerogel. The preparation method of the Fe3O4/graphene aerogelcomprises the steps that the graphene aerogel and a dopamine solution are subjected to a hybrid reaction under the alkalescence condition to obtain a dopamine/graphene aerogel. Then through an alcohol-thermal reaction and calcining, the Fe3O4/graphene aerogel is obtained. The graphene aerogel prepared by the preparation method is specific in structure and high in conductive performance and has few defects, and therefore the obtained Fe3O4/graphene aerogel has better electromagnetic shielding performance.