Narrow line fluorescence spectra of Eu3+:Y2SiO5 crystal are obtained by exciting with Ar+ laser at 514.5 nm, 488 nm and He-Cd laser at 441.6 nm. Complex spectral structure is analyzed and identified, which is understood as originating from taking off the energy level degeneracy of Eu3+ in the host crystal field and the possession of two inequivalent lattice sites of Eu3+ in the host crystal. X-ray powder diffraction pattern of Eu3+:Y2SiO5 shows that the the crystal is monoclinic. The lattice constants a, b, c and β are obtained by a simulation with the measured difraction angles, and found that the lattice constants a, b, c are slightly larger but very close to those of undoped Y2SiO5 crystal.