Anatase $TiO_2$ particles prepared by experiment were used to study the change of crystal structure by calcination temperature. The results were as follows. Crystallite size of anatase $TiO_2$ particles increased with calcination temperature. The rate of increasing the crystallite size of anatase $TiO_2$ particles was decreased below $700^{circ}C$ and was markedly increased above $700^{circ}C$. Unit cell volume of $TiO_2$ was expanded at low temperature and was contracted at high temperature. This result means that the growth of crystallite size was occured in the direction.