The hospitalization rate is an important indicator for measuring the utilization of healthcare services, observing the operation of healthcare security systems, and assessing the allocation of medical resources. Differences exist across countries and data sources in terms of statistical objects, event boundaries, and institutional coverage. From an international comparative perspective, this paper analyzes the definition and statistical sources of China’s hospitalization rate, as well as its comparability with the hospitalization rate indicators of OECD countries. Combining structural and institutional factors, it explores the relative level of China’s hospitalization rate and its underlying mechanisms. The study finds that hospitalization rates vary among different statistical sources in China. After adjusting the statistical definitions, China’s hospitalization rate decreases from its original value but remains higher than that of most comparable countries, with day cases and repeated hospitalizations partially explaining this phenomenon. From a long-term trend perspective, the hospitalization rates of most OECD countries are either slowly declining or stabilizing at high levels. In international comparisons based on aging, economic development level, and bed supply, China’s hospitalization rate is higher than that of most comparable countries, indicating that its relatively high level cannot be fully explained by demographic structure, development stage, or resource supply alone, and requires further analysis of institutional factors. Overall, the relatively high hospitalization rate observed for China in international comparisons is the result of differences in statistical definitions, repeated hospitalizations, medical resource expansion, and institutional incentives.