BaMoO4:Sm3+ phosphor system with a tetragonal structure was synthesized via a high-temperature solid-state method. The charge compensated behaviors, 2Ba2+-> Sm3++M+, where M+ is a monovalent cation like Li+, Na+, and K+ acting as a charge compensator, were investigated in this paper. It has been found that BaMoO4:Sm3+ phosphor by doping with K+ ions show greatly enhanced reddish orange emission compared with pure BaMoO4:Sm3+ sample. Investigation on Sm3+ and K+ concentration-dependent emission spectra indicated that Ba0.84MoO4:0.08Sm3+,0.12K+ phosphor exhibited the strongest reddish orange emission with a CIE values of x=0.55 and y=0.43. After irradiation under the 402 nm ultraviolet (UV) excitation, three emission peaks centered at 561, 598, and 642 nm corresponding to the 4G(5/2) to 6H(J) (J=5/2, 7/2, 9/2) emission lines of Sm3+ were obviously observed, and the lifetimes of three emissions (4G(5/2)-> 6H(J=5/2, 7/2, 9/2)) have been calculated based on the measured decay curves.