In the context of current energy and environmental crises, dry reforming of methane (DRM) is an important reaction. While non-noble metal catalysts are highly promising for real-world DRM applications, they often suffer from deactivation due to sintering and carbon deposition. In this study, ultrafine bimetallic NiCo nanoparticles encapsulated in silicalite-2 (S-2) were prepared via an in situ growth method. Density functional theory in combination with microkinetic modeling was used to understand the influence of the alloy on reaction kinetics and the resistance to carbon deposition. Elemental segregation was observed during the activation stage, wherein the Ni and Co atoms migrated toward the outer surface and center of the NiCo alloy, respectively. Subsequently, the Ni0.2Co0.3@S-2 catalyst prepared using the optimized Ni/Co ratio showed stable and high CH4 and CO2 conversions for 100 h with no carbon deposition. The confinement effect together with precisely balancing the carbon and oxygen content on the surface of the catalyst contributed to its high catalyst performance. This work is expected to provide relevant guidance for studying the evolution of catalyst structures via material dynamics elucidation.