明末劉蕺山的思想呈現多元複雜的面貌，在理氣、心性論間的關係上，一方面強調「氣」，一方面又強調「性理」的超越性，又以「心」作為主體，因此學界對於其哲學定位歷來眾說紛紜。此中關鍵處在於蕺山對於「形而上下」的看法頗具特色：「形上」即「形下」，其不能離開「形下」而論，但又有主宰之尊，使得「氣」、「理」、「心」、「性」皆統為一，又不失分際。因此將著力處理其「形上形下」的關係，首由蕺山反對朱子之言論進行分析，展現蕺山的疑慮與立論角度，建構其理氣、心性之間關係，凸顯其「形上形下」的一體性；其次，點出蕺山思想中超越的一面，呈現其「形上形下」關係的複雜性；最後，區分出蕺山「形上形下」思想的層次，強調應將「邏輯概念」與「實際存有」的層次分開，找尋分合之間的平衡點，並與朱熹之義理體系進行比較，以更為全面而清晰地理解、呈現蕺山思想之內涵與意義

The Ming Dynasty's Confucian Scholar Liu Jishan's thought is very complicated. He not only emphasized ＂qi＂ but also placed emphasis on ＂li＂'s transcendence. Furthermore, he thought that ＂mind＂ is our moral subject. Because of these, for long his philosophy is hard to be found the orientation. The critical factor is about his thought of ＂metaphysics and physics＂. Liu Jishan thought that ＂metaphysics＂ is just ＂physics＂, and it can't leave ＂physics＂. But ＂metaphysics＂ still got dominance. According to this, ＂qi＂, ＂li＂, ＂mind＂, and ＂human nature＂ are unified, but there still got differences between them. The topic will be approached from three aspects: First, to confer the unity of Liu Jishan's thought of ＂metaphysics and physics＂ from discussing his opposing opinions about Zhuzi's theory. Secondly, to show the transcendental part of Jishan's theory. Thirdly, to differentiate and find a balance between ＂logical concept＂ and ＂actual existence＂ of Jishan's theory.And, comparing the philosophies between Liu Jishan and Zhuzi to understand Jishan's meanings and thoughts