Purpose of this study is to re-compute and analyze the hospitalization rates of residents in China and explore the methodology of systematic review in health policy research.Methodology:DThanks to a history of 90 years,USMLE has evolved into a mature system of international recognition in the industry.This paper covers the history and changes of USMLE and details its goals construction and implementation,examination question selection model,procedures and principles,selection of criteria and the development trends.