In this paper, the different influences of lanthanum (La) and cerium (Ce) species on the stability of Y zeolite were studied by X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), and multinuclear (27A1, 29Si) solidstate nuclear magnetic resonance spectroscopy (NMR). it was found that the stability of Y zeolite could be enhanced by the introduction of La or Ce species; however, the former effect was more remarkable than the latter. These results were also confirmed theoretically by density functional calculations. There was a strong interaction between the rare earth (La or Ce) species and Y zeolite clusters, which restrained the formation of extra-framework aluminum and enhanced evidently the stability of Y zeolite. Furthermore, the interaction between La species and Y zeolite was stronger than that of Ce species with Y zeolite.