The invention relates to a preparation method of layered strontium titanate. The preparation method comprises the steps of weighing tetrabutyl titanate and strontium nitrate according to the stoichiometric ratio of SrO(SrTiO3); adding a complexing agent into an ethanol solution of the tetrabutyl titanate, and stirring until the complexing agent is dissolved so as to obtain a mixed solution; addinga strontium nitrate solution into the mixed solution, evenly mixing, and then heating to obtain uniform and transparent sol; standing and then drying to obtain dried gel; grinding the dried gel, andthen sintering to obtain the layered strontium titanate. The preparation method provided by the invention adopts a sol-gel method, so that the pure-phase layered strontium titanate can be obtained; the obtained layered strontium titanate is uniform in particle size distribution, obvious in preferred orientation, high in diameter-to-thickness ratio and obvious in two-dimensional characteristics; after the preparation method is adopted, the sintering temperature is effectively reduced; furthermore, impurities are not easily introduced in a preparation process, and the technology is simple in process and convenient to operate; when the layered strontium titanate powder is applied to thermoelectric materials, the transverse thermoelectric parameters of the thermoelectric materials can be effectively improved due to the characteristics such as superior thermoelectric properties and natural preferential orientation growth of the layered strontium titanate.