The invention relates to a reinforcing and toughening modified nano-polystyrene/carbon nanotube/epoxy nanohybrid material and a preparation method thereof. The hybrid material comprises, by weight, 50-80 parts of epoxy resin, 0.1-5 parts of nano-polystyrene, 0.01-5 parts of carbon nanotubes and 15-20 parts of a curing agent. The preparation method concretely comprises the following steps: preparing modified polystyrene powder; carrying out electrospinning to prepare polystyrene microspheres; adding nano-polystyrene particles and carbon nanotubes to the epoxy resin, and standing the obtained mixture at room temperature; and performing primary mechanical stirring, adding the curing agent, continuously carrying out secondary mechanical stirring, pouring the obtained mixture into a rubber moldpreheated at 120 DEG C, curing the mixture for 5 h, cooling the cured mixture to room temperature, and opening the mold to obtain the target product. The problem of easy agglomeration of unmodified nano-polystyrene in an epoxy resin matrix is solved, and the presence of the modified polystyrene promotes the uniform dispersion of the carbon nanotubes, so the tensile strength and the toughness of the hybrid material are obviously improved, and the hybrid material has an electrical conduction property.