Lithium niobate powders were prepared by mechanochemical treatments using Li2CO3 and Nb2O5 as raw materials. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) were employed to evaluate the morphologies and structures of samples. The mechanism of LiNbO3 formation of the ground mixture samples was discussed. The crystal structure of mixture was collapsed into a disordered structure, which increased with increasing grinding time. At the same time, the specific surface area increase and the bond energy reduction of the mixture occurred. Consequently, high energy ball milling enables increase of the internal energy, reduction of the activation energy, and improvement of the uniform mixing stage, which resulted in direct formation of singal phase LiNbO3 at a low temperature (500°C). However, the temperature must reach 1200°C for the traditional method.