The invention provides a preparation method of graphene-carbon nanotube hybrid sponge. The preparation method comprises the following steps: preparing carbon nanotube sponge; preparing polystyrene microspheres; preparing graphene oxide-coated polystyrene microspheres; dispersing graphene-coated polystyrene microspheres in an aqueous solution, pouring the obtained solution into the carbon nanotubesponge in a vacuum manner, and carrying out a freeze drying process to obtain a graphene/polystyrene microsphere/carbon nanotube sponge material; and heating the obtained graphene/polystyrene microsphere/carbon nanotube sponge material to remove the polystyrene microspheres and reduce the graphene oxide in order to obtain the graphene-carbon nanotube hybrid sponge. The carbon nanotube sponge is used as a precursor, the graphene-carbon nanotube hybrid sponge is prepared by adopting the vacuum pouring process, and graphene is introduced into the carbon nanotube sponge, so that the specific surface area of a reinforcement body is increased, the conductivity of the carbon nanotube sponge is improved, and the electromagnetic shielding effect is improved.