Crystallization peak temperature was measured for Li2O.2SiO(2) glass with various number densities of nuclei induced by long heat-treatment (similar to405 h) at 460degreesC. Its crystallization process of Li2O.2SiO(2) glass was simulated numerically in order to examine the effect of the initial size of nuclei on crystallization behavior, and the relationship between crystallization peak temperature and the number density of nuclei in the glass was considered. It was found that the effect of nuclei size is not significant when the heat-treatment temperature is lower than 460degreesC. By considering the effect of nuclei size, number density of nuclus was evaluated by DTA method accurately. (C) 2003 Kluwer Academic Publishers.