Nanocomposites for magnetic nanoparticles exhibit a unique character of superparamagnetism, a character of strong responsive to a magnetic field without magnetic attraction among the particles themselves. With proper designs on composition and surface modification, nanocomposites of magnetic nanoparticles can adsorb and degrade pollutants in water and air. The removal and separation of used nanocomposites from environment could be performed using a magnetic force, which is highly efficient in selectivity and energy saving. With this technology on magnetic nanomaterials, pollution control and environmental pollution remedies could be achieved.