The invention relates to an oil-water interface method for preparing BaTiO3 nanoparticles. The oil-water interface method for preparing the BaTiO3 nanoparticles comprises the steps that BaCl2, sodium oleate and tetrabutyl titanate are dissolved in deionized water, then cyclohexane is added into the deionized water, stirring is carried out at 40 DEG C, and an oil soluble precursor is obtained; sodium hydroxide is dissolved in the deionized water and stirred to be uniform to obtain a hydroxyl precursor; the solution is magnetically stirred after being mixed to obtain a precursor solution, the precursor solution is transferred to a reaction kettle to be subjected to a reaction for 12-24 h at 180 DEG C, then separation washing, drying and calcination are carried out, and finally the BaTiO3 nanoparticles are obtained. The oil-water interface method has the advantages of being easy and convenient to implement, good in repeatability, capable of achieving mass production and low in cost. The prepared excellent oil soluble BaTiO3 nanometer powder is uniform in particle size distribution, and the application prospect is good.