Generally, strong acid sites were understood as the main active site for the methanol-to-olefin(MTO) reaction over the ZSM-5 catalyst. In this study, the correlation between the catalytic activity and the extent of deactivation by coke deposition was found to be quite proportional mainly due to the changes in the amount of the strong acid sites. The kinetic expression including the catalytic deactivation was able to be derived and the deactivation rate constants were estimated. From this kinetic study of catalytic deactivation in the MTO reaction, the value of the deactivation rate constant(k'_d) was 0.195 hr^-1 at 350℃. From the results of NH₃-TPD measurement, it was found that the amount of strong acid sites were controllable by the ion-exchange of metal counterion. The selectivity and yield of propylene were found to be proportional to the amount of strong acid sites. Regeneration of the deactivated catalyst was carried out by burning off the deposited carbon using an air and the catalytic activity was recovered quite significantly. It was found that the estimated deactivation rate constants represent the degree of deactivation fairly well. The regeneration efficiency was gradually decreased by repeating regeneration.