A series of NaSr1−x−yPO4:xTb3+:yCe3+ (x = 0.04) phosphors doped with Ce3+ at different concentrations were synthesized by microwave-assisted sintering. The crystal structure and luminescent properties of the phosphors were carefully investigated. X-ray diffraction (XRD) analysis confirmed that all the samples were matched with the standard patterns of NaSrPO4, even though the doping concentrations of Ce3+ ions are increased to y = 0.07. All particles prepared by microwave-assisted sintering are very nearly spherical, except at the concentration of 0.07, at which they reveal a smooth and polygonal structure. The photoluminescence measurement shows that the major emission peak was located at 547 nm, approximating a green luminescence, which corresponds to a 5D4-to-7F5 transition, and the optimal Ce3+ concentration, which was 0.01, was observed. Moreover, the chromaticity (x, y) is changed with increasing Ce3+ concentration.