Eu 2+ -activated Ba 2 CaMg 2 Si 6 O 17 phosphors were synthesized by conventional solid-state reaction. The phase formation was confirmed by X-ray powder diffraction measurement. The photoluminescence excitation and emission spectra were investigated. The phosphor presents blue-emitting luminescence. The crystallographic sites of Eu 2+ ions in Ba 2 CaMg 2 Si 6 O 17 host were discussed on the base of luminescence properties and the crystal structure. The lightly Eu 2+ -doped sample shows one luminescence center for the Eu 2+ ions on Ba 2+ sites, while there are two luminescence centers for the Eu 2+ ions on both the Ba and Ca sites in heavily Eu 2+ -doped sample. The dependence of luminescence intensity on temperatures and the activation energy (ΔE) for the thermal quenching were reported. The phosphor shows an excellent thermal stability on temperature quenching because of the special layered structure of Ba 2+ ions in the interlayer between SiO 4 layers.