A novel blue emitting phosphor, Na4CaSi3O9:Ce3+, was prepared by the conventional solid-state reaction method. Na4CaSi3O9:Ce3+ was structurally characterized by X-ray powder diffraction. The phosphor can be efficiently excited by near ultraviolet light, and shows blue broadband emission centered at about 430 nm. The Na+ content of Na4CaSi3O9 influences the luminescent properties of Ce3+. The luminescent intensity of the phosphor is a function of Ce3+ concentration. With increasing Ce3+ concentration, the luminescent intensity increases until 4 mol % Ce3+, and then decreases due to non-radiative energy transfer. The investigation shows that Na4CaSi3O9:Ce3+ phosphor is a potential blue phosphor for solid state lighting.