Chen Tuan, also known as Chen Tuan, was a Taoist scholar from the late Southern Song Dynasty to the early Yuan Dynasty, especially famous for his contributions to the theory of the number of images in the Book of Changes. His theory combined the Taoist view of the universe and the theory of the Book of Changes, and put forward many unique insights, which had a great impact on both Taoism and the Book of Changes. Chen Tuan believed that everything in the universe has its own internal laws and order, which can be understood and predicted through the image mathematics of the Book of Changes. He was very well-educated in the study of Yi, and put forward many new theories on the yin and yang five elements and the evolving universe. His profound interpretation of the Book of Changes and his exploration of philosophy, cosmology, natural science and the wisdom of life made him an important figure in the history of ancient Chinese thought and culture. In addition, Chen Tuan is also a practitioner, cultivating inner alchemy, pursuing the unity of body and mind and immortality. Chen Tuan lived in a turbulent era, but through his cultivation and learning, he found a spiritual sustenance that transcended the turbulence of the times, which had a profound impact on the development of Taoism, especially Quanzhen Dao. His theories and practices, especially his in-depth research and application of I Ching elephants, are still valued by Taoist believers and Yi Studies researchers today.