Anatase TiO₂particles prepared by experiment were used to study the change of crystal structure by calcination temperature. The results were as follows. Crystallite size of anatase TiO₂particles increased with calcination temperature. The rate of increasing the crystallite size of anatase TiO₂particles was decreased below 700℃ and was markedly increased above 700℃. Unit cell volume of TiO₂was expanded at low temperature and was contracted at high temperature. This result means that the growth of crystallite size was occured in the direction.