在宋明儒學家中，以朱子對佛老的批評，最為嚴厲，非惟視佛老為異端，更提出「釋老之學盡當毀棄」、「勢須用退之盡焚去乃可絕」。朱子何以如此激烈地力闢佛老，本文首先從三方面探討其內在原因：1.文化危機的體認2.儒門淡薄的憂患3.承繼道統的擔當。 復次，朱子對佛老的批評是否允當？其是「系統內的批評」，抑或是「系統外的批評」，本文從其「以老子為楊墨」與「老子是權謀法術」為例，考察其說的允當性，並試圖就其批評，內在於老子義理，提出平議，冀能尋繹致成朱子誤解的原因所在。 宋明儒學家因反佛老，故視佛老學說為禁忌，此一現象導致宋明儒者本身的對立與內訌，亦且成為其抉發儒學本體論架構的自我限制，這是宋明在文化大格局上的不足，而如何跨越此種禁忌，亦是我們當代文化工作者不得不正視的時代課題。

　　　　　Among Neo-Confucian philosophers, Chu Tzu is the one who criticizes Lao Tzu most severly. Chu Tzu views Lao Tzu as a heretic. In this article, first, I inquiry onto the question of why Chu Tzu refutes Buddhist and Taoist. This inquiry is approached from the following three respects: 1. the cultural crisis, 2. the Confucian worries, and 3. the succession of Confucian Tao. And secondly, I look into if Chu Tzu’s criticism is appropirate and whether his criticism is made from the point of view within Lao Tzu’s own system. I examine its appropriateness by taking “Lao Tzu is aYung Mo” and “Lao Tzu is a Fa-Shu-Chia.” as two examples, and try to find out what makes Chu Tzu have such a misunderstanding by tracing back to Lao Tzu’s own thought to see Chu Tzu's criticism.