NaYF4:Er,Yb/Bi2MoO6 core/shell nanocomposite was designed and prepared for the first time based on upconversion. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution TEM (HRTEM), energy dispersive X-ray spectroscopy (EDS) and diffuse reflectance spectra (DRS). The results revealed that the as-synthesized NaYF4:Er,Yb/Bi2MoO6 consisted of spheres with a core diameter of about 26 nm and a shell diameter of around 6 nm. The core was upconversion illuminant NaYF4:Er,Yb and the shell was Bi2MoO6 around the core, which was confirmed by EDS. The NaYF4:Er,Yb/Bi2MoO6 exhibited higher photocatalytic activity for the photodecomposition of Rhodamine B (RhB) under the irradiation of Xe lamp and green light emitting diode (g-LED). The mechanism of the high photocatalytic activity was discussed by photoluminescence spectra (PL), which is mainly attributed to upconversion of NaYF4:Er,Yb in the NaYF4:Er,Yb/Bi2MoO6 nanocomposite and the core shell structure. (C) 2014 Elsevier Ltd. All rights reserved.