<p>SrTiO₃(STO) is an important grain boundary layer capacitor material and has extensive applications in integrated and microwave circuits. In this work, SrTiO₃ precursor powder was prepared using the solid-phase sintering method, and STO ceramic capacitors with a thickness of 0.2&#xa0;mm were fabricated by the tape casting method. Effects of synthesis conditions, especially synthesis temperature and time, on the structure, morphology and electrical properties of STO were investigated through characterization methods such as XRD, SEM, TG-DSC, and dielectric property measurements. The relationship between the morphology and grain size of STO and its dielectric properties was also explored. The results indicate that 1250 ℃ and 1440 ℃ are the critical temperatures(beginning and complete formation) for preparing SrTiO₃ through solid-state sintering of SrO and TiO₂. When the temperature is below 1250 ℃, SrO and TiO₂ remain in initial raw material powder states, and SrTiO₃ cannot be synthetized. As the temperature exceeds 1250 ℃, the contact interface between SrO and TiO₂ begins to react, and result in the formation of SrTiO₃ through a solid-phase reaction. In addition, 1440 ℃, as the eutectic point between SrTiO₃ and TiO₂, is the optimal temperature for synthesizing SrTiO₃ with mature grains and the best electrical performances. Moreover, the results show that with the increase of synthesis temperature and time, the grain size of STO first increases, and then decreases if further increasing synthesis temperatures and time. When the synthesis condition is 1440 ℃ × 2&#xa0;h, the average size of STO grain reaches a maximum value of 1.76&#xa0;μm and STO has the best dielectric properties with a dielectric constant of 25,000, a loss of 1.25% and a capacitance temperature stability coefficient of + 6% to -9% in the range of -50 ℃ to + 125 ℃, which is a kind of STO ceramic material with a good comprehensive performance in practical application.</p>