Nanoparticles of erbium-doped calcium fluoride were synthesised by the coprecipitation method. Micromorphology of the obtained nanoparticles was observed by transmission electron microscopy. The nanoparticles were hot-pressed in a vacuum environment to achieve Er: CaF2 transparent ceramic. X-ray diffraction analysis confirmed the crystallization of a single fluorite phase after sintered. Transmittance spectrum of Er: CaF2 ceramic sample was measured, and the transmittance at 1200 nm reached about 87%. Microstructures were characterized using field-emission scanning electron microscopy. The luminescence spectrum of Er: CaF2 transparent ceramics under 488-and 978-nm excitation was measured and discussed. It was evidenced that strong cross-relaxation processes between Er3+ ions occur at high dopant concentration, and favoring the red emission at the expense of the green one.