Curcumin is a natural organic substance that has attracted much attention because of its medicinal properties. Because of its immunomodulatory, anti-inflammatory, analgesic and anticarcinogenic effects, medicines containing curcumin are used to treat fever, jaundice, and skin diseases, especially cancers. The luminescence resonance energy transfer (LRET) technique is a powerful and widely used analytical method to verify analytes. In this work, we propose core/shell-structured upconversion nanoparticles (UCNPs) modified with amino groups as a luminescence probe for curcumin detection via LRET; the method is highly sensitive, rapid, easy to operate, and simple and has a low detection limit. In the detection process, curcumin can be brought into close proximity to the core/shell-structured UCNPs@NH2 via electrostatic attraction and absorb the luminescence of the UCNPs. The results show that the detection limit of curcumin is 0.625 ng/mL. This study indicates that core/shell-structured UCNPs@NH2 could be used as a valuable probe to detect curcumin.