A new type of (0.7-x)Bi0.5Na0.5TiO3-0.3Sr(0.7)Bi(0.2)TiO(3)-xLaTi(0.5)Mg(0.5)O(3) (LTM1000x, x = 0.0, 0.005, 0.01, 0.03, 0.05 wt%) lead-free energy storage ceramic material was prepared by a combining ternary perovskite compounds, and the phase transition, dielectric, and energy storage characteristics were analyzed. It was found that the ceramic materials can achieve a stable dielectric property with a large dielectric constant in a wide temperature range with proper doping. The dielectric constant was stable at 2170 +/- 15% in the temperature range of 35-363 degrees C at LTM05. In addition, the storage energy density was greatly improved to 1.32 J/cm(3) with a high-energy storage efficiency of 75% at the composition. More importantly, the energy storage density exhibited good temperature stability in the measurement range, which was maintained within 5% in the temperature range of 30-110 degrees C. Particularly, LTM05 show excellent fatigue resistance within 10(6) fatigue cycles. The results show that the ceramic material is a promising material for temperature-stable energy storage.