Yu Yan made significant contributions to the study of the Zhou Changes by combining Confucian teachings with Daoist approaches. He wrote the Zhouyi jishuo, refining it four times to better represent ancient sages' meanings. He also delved into Daoist practices, discovering the secrets of the Taiji diagram and alchemical processes. By integrating Shao Yong's diagram-based approach and Wei Boyang's alchemical theories, Yu Yan expanded the understanding of the Changes in Daoism.