Schistosomiasis has influence on people’s security and daily life significantly, while cercarial stage of the schistosome life-cycle is the only infectious period. To detect cercarial efficiently, we synthesized rare-earth upconversion nanophosphors UCs-Ni loaded with niclosamide. The fluorescence of UCs-Ni was demonstrated by the fluorescence emission spectra. The cell imaging test illustrated that UCs-Ni was biocompatible, cell-permeable and suitable for cercariae imaging. When it has been utilized for cercariae imaging, we found that the UCs-Ni could penetrate into cercariae.