Luminescent Ca 1−x F 2+x :Eu x nanoparticles were synthesized by a chemical co-precipitation method in an ethanol solution. The Ca 1−x F 2+x :Eu x nanoparticles exhibit a sphere-like morphology with particle diameter of about 15–20nm. With increasing concentration of Eu 3+ ion the intensity of XRD diffraction peaks decreased significantly and full width at half-maximum of the peaks increased gradually, which indicated that more Eu 3+ ions resulted in the increase of structural defects. The emission spectrum of Ca 1−x F 2+x :Eu x nanoparticles consisted of a few narrow, sharp lines corresponding to Eu 3+ ions. The luminescence intensity of Ca 1−x F 2+x :Eu x nanoparticles increased with increasing concentration of Eu 3+ ion and reached a maximum at approximately 15mol%.