Red phosphor powders of rare earth Eu3+ activated La2Mo2–ySyO9 (y = 0–0.07) were prepared by the high temperature solid state reaction, and their crystal structure and photoluminescence properties were investigated. After small amounts’ substitution of S for Mo and incorporation into lattice, samples structure is almost identical with the original and retains cubic phase of host β-La2Mo2O9, as revealed by the X-ray diffraction data. However, unit cell parameters of the lattice decrease gradually with increase of S doping content (y value). Photoluminescence indicates that all the samples exhibit characteristic red emission of Eu3+ (5D0→7F2) located at about 615 nm. Monitored with 615 nm wavelength, linear excitation of Eu3+(7F0→5D2) around 465 nm is the most predominant. In particular, relative emission intensity of the samples is obviously improved after S-doped. The optimum sample shows more than 2-fold emission intensity in comparison with the sample La2Mo2O9:Eu.