Eu3+-activated Ca0.5Sr0.5MoO4 phosphors were prepared by a high-temperature solid-state reaction method. The X-ray diffraction patterns revealed that the obtained samples had a pure tetragonal phase. Under 393 nm excitation, all the samples exhibited the characteristic emissions of Eu3+ ions and the photoluminescence (PL) emission intensities showed an upward trend with elevating the Eu3+ ion concentration, while the concentration quenching effect took place when the Eu3+ ion concentration was over 9 mol% and the critical distance was determined to be about 13.09 a"<<. Furthermore, the cathodoluminescence (CL) spectra, which were measured under low-voltage electron-beam excitation, demonstrated that the Ca0.41Sr0.5MoO4:0.09Eu(3+) phosphor had excellent CL performance. Also, the alkali metal ions, such as Li+, Na+, and K+, were used as the charge compensator to modify the PL emission intensity of the Ca0.41Sr0.5MoO4:0.09Eu(3+) phosphor and the phosphor compensated by Na+ ions showed the strongest PL emission intensity.