<p>Subnanometer metal cluster catalysts have garnered significant attention due to their multi-site synergistic catalytic capabilities. However, constrained by classical sintering theory, metal clusters are prone to sintering and growth, which makes it challenging for them to stably exist at high temperatures. Prevailing strategies predominantly focus on the synthesis pathways from atoms to clusters, while overlooking the bidirectional regulation potential of metal particle dynamic reconstruction. This study transcends conventional paradigms by proposing a reverse regulation strategy from particles to clusters. The disadvantage of high temperature is strategically converted into driving forces for particle dispersion through the rational design of catalytic environments and metal-support interactions. Through a comprehensive combination of in situ characterization techniques and theoretical calculations, the interfacial atomic migration pathways and energy evolution during dynamic dispersion are systematically investigated. Furthermore, the formation process and underlying mechanism of stable Ni clusters are elucidated. The optimized 10Ni/30La-CeO₂ catalyst exhibits a remarkably high H₂ production rate (500 °C, 279.2 mmol_H2·g_Ni⁻¹·min⁻¹) and exceptional thermal stability. This work not only provides a methodology for developing thermally stable cluster catalysts but also fundamentally reveals the mechanism of reverse sintering from the perspective of atomic migration kinetics and thermodynamic steady-state reconstruction.</p>