Confucianism is not a religion but plays a religious role in Chinese life and society. The tendency to encourage reproduction exists throughout the Confucian system, including the cosmology, ontology, value system, and ethics, and therefore greatly helps to formulate the strongly pronatalist culture. This analysis examines the impacts of Confucianism on Chinese reproductive behavior, and shows that there is an obvious relationship between China's large population and Confucianism.