The crystal size was determined as a function of reaction temperature, during the crystallization process of NaX zeolite. The measured rate constants for linear growth were as 0.0441$mu extrm{m}$/h at $80^{circ}C$, 0.0595$mu extrm{m}$/h at $90^{circ}C$ and 0.0972$mu extrm{m}$/h at $100^{circ}C$, respectively. The activation energy calculated from the relation between the linear growth rate an the reaction temperature was 43.243kJ/mol. The reaction of crystal growth were revealed as 20 days at $80^{circ}C$, 16 days at $90^{circ}C$ and 9 days at $100^{circ}C$, respectively. Both the final product crystal size an the crystallization time were decreased with increasing reaction temperature.