The phase-transition behavior and thermal stability of Ge2Sb2Te5/Si nano-multilayered films are investigated in this study. Our results reveal that the improvement in thermal stability and increase in the phase-transition temperature are not universal results for all nano-multilayered structures. The stress effect induced by thermal expansion during heating indeed could inhibit the crystallization of Ge2Sb2Te5/Si nano-multilayered films. The interface effect is believed to play a dominant role in thicker films, while the stress effect is active when the layer thickness is decreased. The gradual shift in the Raman peaks' position can support this scenario because they are modified by both the interface effect and the stress effect.