「莊子本性論」是一學術上重要而有意義之論題，唯歷來探討者少且方法稍有瑕疵，本文將對歷來探討莊子本性論之研究法作反省，並提出二種新研究法－「前理論期研究法」與「範疇學研究法」，以對莊子本性論作探究。「前理論期研究法」是直接歸納莊子零散之本性論思想，包括分析莊子所論「常」、「天」、「真」、「復」、「盡」等概念，以說明其主張吾人「永具」、「生具」、「現具」、「本具」、「皆具」成聖本質。「範疇學研究法」則基於哲學思想之各範疇間為有機組合，故經由弄清其他範疇之義理可間接推知本性論思想，這些範疇包括：現況論、價值論、功夫論、境界論等，透過此四論考察可相當程度確定莊子本性論。莊子處本性論萌芽初期，內七篇中尚無「性」之字詞概念，更遑論本性論系統，但透過本論文之探究，發現莊子實有甚強之本性論主張，他確信吾人生而本具皆具成聖質素；此種主張實與儒家佛家之立論無殊。

"Chuang Tzu's theory of human nature" is an important and significant academic topic. However, there are scanty related studies, and the approaches are unsatisfying. This paper reviews the past approaches on Chuang Tzu's theory of human nature, and proposes two new approaches-"first theoretical stage approach" and "category theory approach" to study Chuang Tzu's theory of human nature. "First theoretical stage approach" directly generalizes Chuang Tzu's fragmental thoughts of theory of human nature, including his ideas such as "Chang", "Tien", "Chen", "Fu" and "Ching" to describe the sage quality such as "Yung Chu", "Sheng Chu", "Hsien Chu", "Pen Chu" and "Chieh Chu". "Category theory approach" is based on the combination of different categories of philosophical thoughts and indirectly probes into theory of human nature by clarifying the principles of other categories, including: present theory, value theory, skill theory and boundary theory which can validate Chuang Tzu's theory of human nature to some degree. Chuang Tzu is in the early stage of theory of human nature and the concept of "nature' is not found in the seven chapters, not to mention the system of human nature theory. However, the research finding of this paper demonstrates that Chuang Tzu has significant statements on theory of human nature and he suggests that human nature involves the quality of the sage. The idea matches that of the Confucian school and Buddhism.