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。從修道證道的意義上說，內丹修煉是否有成關鍵就在於能採取大、小藥進而促使元精、元炁、元神的轉化。採了真種小藥以後，大藥的採取更具關鍵。也由於煉己、調藥、產藥、採藥、封爐、煉藥均需遵循一定的程序，採大藥的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. For the meaning of reaching the essence of self-cultivation, the achievement of Nei Dan Medication relies on the acquisition of minor and major medication as well as the transformation of energy, chi and spirit. After the acquisition of minor medication, the self-cultivation of major medication will become more crucial. 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＂. Since late Ming Dynasty and early Qing Dynasty, ＂Wu Liou Tan Fa＂ has been spread widely, and has strongly influenced Taoism. Those are the reasons why this paper is centered on ＂Wu Liou Tan Fa＂. 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.