This paper examines how informal institutions shape political stability in autocratic regimes by analyzing succession norms in ancient China. We argue that the institutionalization of vertical succession norms (VSNs)—which limit legitimate successors to the monarch’s sons—narrows the candidate pool and facilitates elite coordination in selecting the successor. Using an original dataset of 358 monarchs from 17 states during the Spring-Autumn and Warring States eras (771–221 BCE), we find that VSN institutionalization reduces the likelihood of elite-led deposition. To address endogeneity, we conduct a sub-sample analysis that restricts comparisons to monarchs who inherit personal power from their predecessors and employ an instrumental variable approach based on ancestral distance to royal lineages. We also show that VSNs mitigate the destabilizing effects of elite competition. Our findings contribute to the literature on authoritarian survival and informal institutions by demonstrating that succession rules can promote political stability even before they are codified.