Abstract: We investigated the crystallization of NaYand especially the transformation of NaYto NaPtype zeolite from an initial gel of batch composition 3.3Na₂O·Al₂O₃· 10SiO₂·200H₂Oat 100℃. We found that there are three stages in the whoie process: the nucleation and crystal growth of NaYtype zeolite, the nucieation of NaPand the dissolutian of NaYand the crystal growth of NaPtype zeolite.In order to investigate the mechanism of this process.We proved the formation of nuclei of NaYand NaPtype zeolites in liquid phase by using the electron diffraction technique. We used the electrom micrograph, X-ray diffraction, TMS-GCand(HRMAS) solid state Si-29NMRtechnique comprehensively to investigate the changes of particle size and morphology of zeolite, the existing species and their distribution of poly-silicates in liquid and solid phases and the change of zeolite structure in the process of transformation of NaYto NaPc. Amore detailed liquid phase transportation mechanism of transformation was suggested.