Poly (acrylic acid)-functionalized magnetic nanoparticles (Fe3O4/PAA) were synthesized by polymerization of acrylic acid initiated by UV light. CdS-modified Fe3O4/PAA composite particles (Fe3O4/PAA/CdS) were photochemically prepared in aqueous solution containing cadmium sulfate and sodium thiosulfate with Fe3O4/PAA as the magnetic core. The composite particles were characterized by infrared spectroscopy (IR), X-ray powder diffraction (XRD), transmission electron microscopy (TEM), photoluminescence measurement (PL), and vibrating sample magnetometer (VSM). The results show that the mean size of Fe3O4/PAA/CdS spheres with core-shell structure and rough surface is about 155 nm and the size distribution is rather wide. The composite spheres also exhibit luminescent and quasi-superparamagnetic properties. Besides, the magnetic composite spheres possess excellent activity as a recyclable photocatalyst for the degradation of Rhodamin B when exposed to visible light irradiation and can be covered by a magnet from aqueous solution within 2 min.Cited