Biocompatible NaREF4 (RE=0.4Y+0.4La+0.2(Yb,Er,Tm)(molar ratio)) upconversion nanoparticles (UCNPs) with strong visible fluorescence were synthesized by a solvothermal method and subsequent surface modification. Modulated upconversion lu-minescence emission spectra were obtained via changing the doping. In vitro andin vivo bioimagings were carried out with shrimps. The upconversion nanoprobes with an acidic/PEG hybrid ligand could quickly capture the basic Rhodamine-B (RB) in shrimp cells and formed a close UCNPs@RB system. The residual organic dye RB in shrimps could be detected on the basis of luminescent reso-nance energy transfer (LRET). It could be rapidly addressed based on LRET detection that RB residue existed in the shrimps after incubating in the aqueous solution of RB higher than 3μg/mL for 12 h.