A series of Ca4.99(PO4)3F:1%Eu3+, 1%X (X = Li+, Au3+, and Bi3+) nanoparticles are prepared using hydro-thermal method, with an average size of 33–62 nm. We study the improved photoluminescence properties of Ca4.99(PO4)3F:1%Eu3+ by co-doping with Li+, Au3+, and Bi3+ ions, respectively, and the enhancement of the emission intensities of Eu3+ is observed in these samples. The effects of Li+ acting as a charge compensator, Au3+ as a plasma surface sensitizer, and Bi3+ as an energy conversion agent are discussed. The results show Ca4.99(PO4)3F:1%Eu3+, 1%X nanoparticles are a promising candidate as a red component for near-ultraviolet light-emitting diodes.