A series of novel orange-red emitting phosphors K3Y1-xSmxB6O12 (x = 0.005, 0.01, 0.02, 0.03, 0.05, and 0.1) were synthesized via high temperature solid-state reaction. Their phase purity, crystal structure, photoluminescence property and decay behavior were investigated in detail. XRD results indicated the as-prepared phosphors were single-phases and crystallized in trigonal structure. Upon excitation with 403 mu, the phosphors emitted orange-red emission, which was ascribed to the (4)G(5/2) -> H-4(J) (J = 5/2, 7/2, 9/2, 11/2) transitions of Sm3+. The optimal doping concentration of Sm3+ ions in K3YB6O12 was about 0.05, beyond which the electric dipole -dipole interaction between Sm3+ and Sm3+ induced the luminescence quenching of Sm3+. The results showed that the orange-red emitting phosphors K3YB6O12:Sm3+ may have potential application in white light emitting diodes.