Morphology-controlled BaTiO3 nanostructures such as spherical, cube-shaped and rod-shaped BaTiO3 were synthesized by using molten-salt synthesis method. The products were all synthesized by reaction of BaO/BaCO3 and TiO2 with a eutectic mixture of NaCl-KCl flux at 700 °C for 1 h. Powder X-ray diffraction device, field emission scanning electron microscope and transmission electron microscope were used to investigate the structure and morphology of the products. The proposed synthetic mechanism of BaTiO3 in the molten salt was also provided to illustrate in-situ transformation mechanism of BaTiO3 nanostructures in the reaction. It reveals that the initial shape of the titania and the dissolution rate of the initial precursors critically determine the shapes of the final products.