The alkaline earth metal magnesium chlorosilicate M7Mg2(SiO4)4C12:0.08Eu2+(M=Ca,Sr,Ba) phosphors activated by Eu2+ were synthesized by high-temperature solid-state reaction, and the luminescence properties of the phosphors were studied. Results show that all the three phosphors have broadband excitation spectra with ranges of 250-500 nm, 250-450 nm, 250-430 nm, respectively. The composition dependence of the radiation transitions of Eu2+ in the host was discussed. The position of emission peak of Eu2+ moved to short-wavelength and the phosphors emit green (507 nm) and blue (458 nm, 445 nm) light with increasing of radius size of Ca, Sr and Ba ions in sequence