The phase transformation of amorphous bismuth titanate fabricated by sol-gel method was investigated by X-ray diffraction (XRD), transmissions electron microscopy (TEM) and differential thermal analysis (DTA). The experimental results show that the four-step crystallizations were present on heating. The metastable phases Bi2O3 and TiO2 were formed firstly at 433℃, and Bi2Ti4O11 phase was subsequently formed at 488℃ by the reaction between Bi2O3 and TiO2. Sequential reaction between Bi2Ti4O11 and Bi2O3 resultedin the formation of Bi4Ti3O12 phase with tetragonal structure at about 644℃, and stable Bi4Ti3O12 phase with orthorhombic structure was finally formed at about 830℃.