The invention provides a three-dimensional graphene macroscopic body preparation method. According to the invention, the three-dimensional macroscopic body is constructed through hydrothermal self-assembly, and in-situ synthesis of MOFs is realized among the layered structure of the graphene macroscopic body. The multilevel pore-structured three-dimensional macroscopic body provided by the invention has high specific surface area, and facilitates electrolyte ion diffusion and transmission. An internal crosslinking structure formed with graphene and carbon nanotubes serves as a conductive network, and facilitates electron transmission. Therefore, interface resistance is effectively reduced, and the specific capacity, rate and circulation performance of a supercapacitor are improved. The graphene macroscopic body provided by the invention has stable structure, high specific surface area, and high conductivity, such that the graphene macroscopic body can be applied in supercapacitors. The preparation method has the advantages of simple process, easy-to-control reaction process, and less equipment investment. The preparation process does not need to be carried out under a vacuum or high-pressure condition. With the method, large-scale production can be realized.