鄭因百先生於1948年渡海來台任教，為台灣曲學研究的奠基者。本文旨在綜述鄭先生在戲曲方面之研究成果及其在戲曲學史上的意義。鄭先生的戲曲學可分為「戲曲文獻之稽考」、「戲曲體製格律之考訂」、「戲曲藝術之品評」三大面向，而其治學之根柢則為經史考據，得力於乾嘉樸學之傳統。尤其在稽考戲曲文獻方面，編纂目錄、輯逸校勘、考評版本，更充分展現鄭先生徧稽史料、考辨事實的樸學素養。在考訂戲曲體製格律方面，鄭先生針對元雜劇體製中素有疑義之處，如「插曲」、「散場」，進行詳細的比對考辨，提出明確界義。更以二十餘年的心力考訂北曲曲律，完成《北曲新譜》、《北曲套式錄詳解》兩部專書，足為北曲曲律之經典。其考訂之工夫細密精嚴，其底蘊固仍為樸學之治學精神，其方法強調歸納資料、推論律則，則又具有科學實證之意義。在品評戲曲藝術方面，主要從文學的角度來衡量，曲文則是其關注的焦點。鄭先生論評戲曲曲文首重「質地清真」，要代劇中人物立心，深透其情，方能真切動人，這正與其寫詩、讀詩、論詩時「本乎情志」的觀點相通，其根源俱為先生的詩人心靈。

This article will discuss Professor Zheng Qian's contributions to the research on Chinese classical drama. Zheng's studies can be divided into three aspects: textual research, collations of Qu form and art criticism. The foundation of Zheng's research is the Pu Scholar (the textual criticism at Qian-jia Period in Qing Dynasty). Especially on the textual research, including compilations of drama catalogues, collections and revisions of works, and also surveys of versions, Professor Zheng performed profound scholarship of Pu Scholar and accomplished significant achievement. In terms of collations of Qu form, Professor Zheng resolved some controversial issues about the structures of Yüan tsa-chü. Furthermore, the most important parts of Zheng's studies on Qu form are generalizations of the form of tunes and the composing rules of the songsets. In terms of art criticism, Professor Zheng strongly emphasized the essence of the lyrics in Chinese classical drama is sincerity. The language of lyrics needs to meet the inner thoughts of characters. This opinion is similar to Zheng's writing and criticism on poem that originates from the poet's consciousness.