A series of phosphors with the composition of Y2.95-xCaxAl5-xSixO12: Ce3+0.05 (x=0, 0.15, 0.30, 0.45, 0.60, 0.75) were synthesized with conventional solid state reactions. The results of XRD patterns show that in a certain extent, the co-substitution of Ca2+ and Si4+ does not change the garnet structure of samples, while results in the shrink of crystal lattice(The cell parameter of phosphors decreases with the increment of co-substitution content monotonically. The former is in linear with the latter). The measurement of the excitation and emission spectra shows that the co-substitution of Ca2+ and Si4+ make the emission peak move to short wavelength. The amount of blue shift is also in linear with the co-substitution content.