"The Fundamental Purport of The Journey to the West", written by Yi-Ming Liu-a Quanzhen Taoist in Ching Dynasty collects Liu's explanatory comments to "The Journey to the West". By Liu's unique interpreting way, all the demons & spirits characters in "The Journey to the West" are endowed with "Nei-dan" (Inner alchemy) meaning. The principal discussion of this essay, originates from Liu's "Nei-dan" theory and observes how he interprets novel into an entirely different expression style-"Nei-dan" is focused on the study of demons & spirits described in the story.