Double-perovskite Sr2Ca1-2x Eu (x) Na (x) MoO6 red-emitting phosphors were prepared by the citric acid-assisted sol-gel method, and their luminescence properties were investigated as a function of sintering temperature and Eu3+-doping concentration. B-site substituted Sr2Ca0.8Eu0.1Na0.1MoO6 phosphor, in which Na+ ions act as charge compensators, was selected to study the thermal behavior, phase structure, microstructure, and photoluminescence property under different sintering temperatures. The photoluminescence studies on Sr2Ca1-2x Eu (x) Na (x) MoO6 (x = 0.02, 0.05, 0.10, 0.15, 0.2) show that a dominant red emission line at around 594 nm, which is due to the Eu3+ magnetic dipole transition of D-5(0)-F-7(1), is observed under different Eu3+ excitations (396 and 412 nm). Further, Eu3+ dopant content dependent emission spectra investigations of Sr2Ca1-2x Eu (x) Na (x) MoO6 phosphors indicates that, when the Eu3+ concentrations x = 0.05, there are minimum differences between the emission intensity of D-5(0)-F-7(1) transition at 594 nm and that of D-5(0)-F-7(2) transition at 615 nm. With increasing Eu3+ concentration, the variation of the emission intensities between the two transitions keep nearly invariable and Sr2Ca0.8Eu0.1Na0.1MoO6 phosphor has the strongest red emission in this series.