Stoichiometric lithium tantalate (SLT) powder was prepared by a solid-state combustion method from the raw powder of Li2CO3, Ta2O5, and urea, which is characterized by a short reaction time and relatively low temperatures. The urea, added into the mixture (Li2CO3 and Ta2O5), serves as a fuel and an inducer to produce intermediate compounds and cause a solid-state combustion reaction as well. Various temperatures and urea contents were employed to optimize the synthesis of SLT. The chemical process and the quality of LiTaO3 powder were investigated by X-ray diffraction, electron microscope, thermogravimetry, and Raman spectroscopy. The optimized synthesis shows great capability to reduce the volatilization of lithium-ion and presents an efficient way to manufacture high-quality SLT.