In this work, the La(OH)3 nanorods were successfully synthesized by precisely regulating the parametersof the hydrothermal method. Then, a series of Ni-based CO2 methanation catalysts were fabricated via theincipient-wetness impregnation and deposition–precipitation methods by employing the La(OH)3 nanorodsas the supports. The influences of the support morphology and the preparation method on the metalsupportinteraction, Ni dispersion, and the surface basicity were carefully investigated based on varioustechniques, such as XRD, SEM, H2-TPR, CO2-TPD, XPS, ect. It was found that the rod-shaped La(OH)3 supportedcatalyst prepared by the deposition–precipitation method performed the optimum activity andstability. The reason for this could be derived from the confinement effect of the crystal plane of therod-shaped support, which would promote the formation of the strong metal-support interaction andthe construction of the Ni-La interface with high activity. Furthermore, the online-tandem TG-MS andin-situ DRIFTS technologies were used to investigate the thermal decomposition performance of the catalystprecursors in the calcination process and the reaction intermediates of the CO2 methanation. Therefore, the fundamental roles of support morphology and catalyst preparation method were expectedto direct the advancement of the Ni-based nanostructured catalysts with outstanding low-temperatureperformances.