Aromatic amine modified 3D porous graphene aerogel was prepared through chemical reduction and self-assembly of graphene oxide sheets in one step by using diaminodiphenylmethane (DDM) as a reducing agent, modifying agent, and curing agent. Subsequently, the DDM-modified graphene aerogel (DGA) was fully infiltrated with epoxy resin to obtain the DGA/epoxy composites. The abundant amine groups derived from DDM on the DGA can react with epoxy resin to strengthen the interfacial interaction, further promoted the curing behaviors by significantly lowering the reaction activation energy. The reinforcement of interfacial interaction and well-interconnected frameworks enhanced the effective transfer of stress and electrons in the resulting composites. Thus, the resulting DGA/epoxy composites exhibited excellent compressive properties and high electrical conductivity. This study presented a facile technique for preparing porous graphene aerogel, which simultaneously improved the electrical conductivity and mechanical properties of epoxy composites, and overcame the issues of dispersion and interfacial interaction of traditional nanofillers.