The invention discloses a novel resene-based nanocomposite and a preparation method, a regeneration method and an application thereof, which belongs to the field of an environment functional material. The skeleton of the composite material is macroporous styrene-divinylbenzen copolymerization sphere, active chlorine is subjected to covalent combination on the skeleton, and the nano hydration iron oxide or nano hydration zirconia particles are uniformly distributed in the apertures. The specific surface area of the nanocomposite is 10-80 m<2>/g, the active chlorinity is 0.2-1.5 mmol/g, the mass fraction of Fe/Zr element is 5-25%, and the size of the nano particle is 5-100 nm. Through the steps of annular amide modification-in-situ deposition-chlorination, integration of oxidation function and adsorption function is realized, neighborhood oxidation-adsorption of trivalent arsenic is realized, the resene-based nanocomposite has the advantages of high oxidation capacity, high adsorption selectivity, protrude deep purification performance for trivalent arsenic, and stable regeneration, and can effectively increase the deep processing level of trivalent arsenic in underground water.