A series of high phase purity blue light excitable yellow-emitting La_(3-x)Si_6 N_(11):xCe~(3+) phosphors were synthesized by the high temperature solid state reactions method. The structure and luminescent properties were investigated. The phase structure was studied by means of X-ray diffraction, structures refinements and energy dispersive X-ray spectroscopy. The phosphors effectively excited by the light of450 nm and show intense yellow emission at 535 nm with FWHM of 115 nm corresponding to the5 d →~2 F_(5/2) and 5 d →~2 F_(7/2) transitions of Ce~(3+). In addition,the optimized La_(2.86)Si_6 N_(11):0.14 Ce~(3+) exhibits a weak thermal quenching, which remains 98.2% of the initial emission intensity when heated to 200 ℃,the thermal quenching properties exhibit a modest decline when the temperature returned to room temperature. The above results indicate that La_3 Si_6 N_(11):Ce~(3+) can be regarded as a high promising phosphor for applications in high power white-light LED. A series of high phase purity blue light excitable yellow-emitting La_ (3-x) Si_6N_ (11): xCe ~ (3+) phosphors were synthesized by the high temperature solid state reactions method. The structure and luminescent properties were investigated. The phase structure was studied by means of X-ray diffraction, structures refinements and energy dispersive X-ray spectroscopy. The phosphors were excited by the light of 450 nm and showed intense yellow emission at 535 nm with FWHM of 115 nm corresponding to the 5 d → ~ 2 F_ (5/2) and 5 d → ~ 2 F_ (7/2) transitions of Ce ~ (3+). In addition, the optimized La_ (2.86) Si_6N_ (11) ) exhibits a weak thermal quenching, which remains 98.2% of the initial emission intensity when heated to 200 ° C, the thermal quenching properties exhibit a modest decline when the temperature returned to room temperature. The above results indicate that that La_3 Si_6 N_ (11): Ce ~ (3+) can be considered as a high phosphor for applications in high power white-light LED.