Fluorescence properties of Eu3+ :Y2SiO5 have been investigated. Transitions between 5D and 7Fwere were studied with transmission spectra, fluorescence spectra, photoluminescence excitation ( or absorption ) spectra and site selective fluorescence spectra. The X-ray powder diffraction patt of Eu3 + :Y2SiOs shows that the crystal belong to monoclinic, and lattices constants a, b, c and β are obtained by a simulation with the measured diffraction angles.