A new chlorogermanate compound Ca8Mg(GeO4)4Cl2 (CMGC) was synthesized via high-temperature solid-state reaction for the first time. The crystal structure of CMGC had been refined and determined from the XRD profiles by Rietveld refinement method, which belong to space group Fd-3m with the lattice constants a = b = c = 15.1760(25) Å. Photoluminescence properties of CMGC:Eu2+ phosphors were investigated by absorption spectra, excitation, and emission spectra. The occupy situation and energy transfer were investigated by decay lifetimes and emission spectra under different excitation wavelengths. Thermal stability was also measured. The results show that the absorption spectra of CMGC:Eu2+ phosphors cover from 250 to 500 nm. Under 365 and 435 nm excitation, the emission spectra of CMGC:Eu2+ phosphors show blue-green (centered at 425 and 510 nm) and green (centered at 510 nm) emission, respectively, which attributed to Eu2+ ions occupying different crystal sites. Our results indicated that CMGC:Eu2+ phosphors had a potential application use for white light-emitting diodes.