A method for regulating the structure and properties of the composite nanoabsorbent is provided. This method uses nanoporous chloromethylated polystyrene-divinylbenzene beads as the support material and adopts in situ precipitation method to load dissociative functional nanoparticles thereon; the composite nanoabsorbent of different absorption capacity and absorption speed can be prepared through regulating the pore structure, which is realized herein by means of starting crosslinking reactions through heating chloromethylated beads under existence of the swelling agent and the catalyst; through changing the proportions of different components in the reaction system, modes of heating and time of reaction, the polymer support with different pore structures can be prepared. This invention can successfully regulate the distribution and size of inorganic nanoparticles; the composite nanomaterials prepared by the resin of different degrees of crosslinking present different structures and properties, and the specific structure and properties can be selected in order to meet practical requirements.