The purpose of this thesis is originated from the fact that traditional research on Yu Yen's ideology of the Book of Changes has been confined to two parts, "Doctrine of Changes" and "Phenomenon Science of Changes", while the former comprises the most part. The reason may be due to the effect of classic Confucianism towards the science of the Book of Changes, which results in comparatively less attention and results to and of "Changes in Taoism of Dan." (a combination of Changes and Nei Dan, also refer to Taoism in Changes) This paper; therefore, will discuss Yu Yen's "Changes in Taoism of Dan" through his representative writing, Elaboration on Zhouyi cantong qi (Elaboration on the Agreement of the Three in Accordance with the Book of Changes), including The Exegesis of Zhouyi cantong qi (The Exegesis of the Agreement of the Three in Accordance with the Book of Changes) and The Anecdotal Biography of the Changes.