Our experiment has shown that a grain-oriented structure can be obtained in barium titanium silicate glass ceramics under an isothermal orientation process, without temperature gradient or electric field. A dipole model was developed originally to simulate the isothermal oriented crystallization of BTS glass. Due to the internal electrostatic field induced by the polar crystallites, the additive energy to the crystallization of BTS glass derived from the dipole model is as high as 0.35 eV. Compared with the crystallization activation energy of 2.39 eV, the internal electrostatic field plays a significant role in the crystallization process, which leads to a change in the rates of crystal growth in different directions and a grain-oriented structure.