The invention discloses a polystyrene-graphene oxide composite bulk material and a preparation method thereof. The preparation method comprises the steps as follows: a polystyrene microsphere emulsionand graphene oxide are mixed, an organic solvent which can be dissolved in water and has the surface tension value smaller than 40 mN/m IS ADDED, THE polystyrene microsphere emulsion are demulsifiedand coagulated, and the polystyrene-graphene oxide composite bulk material is obtained after drying. The preparation method is simple in process, green and safe. The invention also provides a preparation method of the graphene-based porous bulk material. According to the preparation method, the polystyrene-graphene oxide composite bulk material is calcined at high temperature in a protective atmosphere, so that the graphene-based porous bulk material adopting a porous structure is obtained and is applied to an electrode material of supercapacitors.