Abstract: The heat of adsorption of NH₃ on HYzeolite has been obtained by CNDO/2 method using (AO)₃ AlOHSi(AO)₃ clusters.The result is closed to the experimental data.It is demonstrated that the proton moving from oxygen on surface of HYzeolite to nitrogen of adsorbate would prefer some site for energetic reason.Appering in the curve of potential energy were two minima.One of minima with distance-1.138Å is near oxygen and the other one-1.720Å is far away from oxygen but near nitrogen.From one minimum to the other the barriar must be climbed over.The value of potential barriar is 9.4kcal/mol from the side of oxygen and 11.9 kcal/mol from the side of nitrogen.Energy difference between the two minima is 2.5 kcal/mol.When NH₃ is adsorbed on cation site, the proton moves a distanc from 1.085Å (between the oxygen and proton) to 1.138Å; The system was evolved energy 21.9kcal/mol.and then the proton climbed over the barriar to arrive at a lower minimum, evolved energy 2.5kcal/mol again, hence the total heat of the adsorption was 24.4 kcal/mol (experiment: 25.7kcal/mol).The turnover number for the proton from the side of nitrogen to the side of the oxygen of the framework in the supercage is 1.92×10⁹ sec^-1 at 400℃.