Long afterglow luminescent materials Sr2-xCaxMgSi2O7:Eu2+,Dy3+ （x=0-1.955）was synthesized by combustion method and characterized by X－ray diffraction,fluorescencespectrum and so on. Its preparing process conditions,the effect of Ca2+ replacing Sr2+ on its Luminescent performance were discussed. The results show it has a single phase and foamy structure,which is easy to be grinded into superfine powders. Its Luminescent property is importantly affected by water dosage(R= nH2O /nTEOS), reducer dosage (H=nreducer /nnitrate), gel grain dosage , gel grain size, arousing-burning temperature and burning time. Its best preparing process conditions are determined. A small quantity of Ca2+ replacing Sr2+ can raise its luminescence performance. Increasing Ca2+ content, its emission peak gradually wave to the long wave traverse, its luminous colors change from blue to yellow. Compared with the sample synthesized by high temperature solid reaction,the emission peaks of the sample synthesized by combustion method distinctly take place red shift.