Alkali earth chlorosilicate of the types Sr 4−x Mg x Si 3 O 8 Cl 4 :Eu 2+ and Sr 4−x Ca x Si 3 O 8 Cl 4 :Eu 2+ have been synthesized from mixtures of SrCO 3 , CaCO 3 , SrCl 2 ·6H 2 O, SiO 2 , MgO, Eu 2 O 3 and proper fluxing agent selected from NH 4 Cl and H 3 BO 3 , which were fired at 900–1000°C for 2–4h, and carbon powder was used as a reducing agent. According to the Van Uitert experimental equation, the color-tunable photoluminescence properties and crystal-lattice environment of Eu 2+ in the host lattice have been studied. Depending on the ratio of Sr 2+ and other alkali earth ions (Mg 2+ or Ca 2+ ) in the host, the position and intensity of different luminescence centers are influenced by Eu 2+ located at different chemical environmental sites. Owing to this, it shows from blue-violet (411nm) to greenish-yellow (565nm) luminescence under 365nm ultraviolet radiation.