內丹功法中有關大、小藥的採取及精、氣、神的轉化，素為丹家所重。然對於內藥、外藥、小藥、大藥之採取各家論述不盡相同。且各派均視如何採藥及採藥之過程為不傳之密。也由於煉己、調藥、產藥、採藥、封爐、煉藥均需遵循一定的程序，採大藥時更有六根震動之景，它的傳授需要明師具體指導和個人在修證過程中細心體會。目前學界對於此一問題的探討較偏重理論方面。著者基於多年修證經驗，希望能夠從修道的內在體驗出發，進而以伍柳丹法為中心對內丹採藥進行專題的研究，期能對內丹修證做出一種契於修道現象本來意義的闡釋。伍柳丹法傳承自全真龍門派，融匯了南宗、中宗及其他各家丹法，體系嚴密、理論完整、次第分明、功法精詳。自明末清初以後，流傳甚廣、影響深遠。故以其為為中心考察比較諸家論述。期待能夠契入內丹修證從而彰顯內丹的原理，進而探索內丹的科學、哲學意義，並且提供自我的修證經驗，期能古為今用，找尋現代意義。

Nei Dan includes the acquisition of major and minor medication as well as the transformation of energy, chi and spirit, which has been valued by Taoism. Yet, different schools have different interpretation about the acquisition of internal, external, minor or major medication. Besides, the process and the method of acquiring Nei Dan medication have been kept as a top secret for years. Since there is a fixed process for self-cultivation, prescription, inspiration, acquisition, sealing and refinement, the explicit guidance of masters as well as the sensitive learning experience of students is needed in order to get the essence. It also happens that we shake our body involuntarily while concentrating on acquiring the major medication. Due to the fact that the study on the acquisition of Nei Dan medication has been done theoretically rather than practically, this paper aims at interpreting, with the aid of author’s personal experience of self-cultivation for many years, the original meaning of Nei Dan medication based on ＂Wu Liou Tan Fa＂. ＂Wu Liou Tan Fa＂ has been passed down from Quan Zhen Long Men and integrated with Nan Zong, Zhong Zong and other schools of Taoism methodology. The system is strict, the theory is complete, the levels are specific and the methodology is done thoroughly. Therefore, it has been widely spread and has had a deep influence ever since the late Ming Dynasty and early Qing Dynasty. Those are the reasons why this paper is centered on Wu Liou Tan Methodology. It is hoped that not only the scientific and philosophical meanings of Nei Dan will be examined in this paper but also its modern value. Moreover, author’s personal experience of self-cultivation for many years will be shared in this paper.