臧懋循是明代曲壇上一重要戲曲家，但他為人所稱道的成就，通常僅止於編選《元曲選》前後集一事而已。如此的瞭解，對臧懋循而言，顯然是不足的。在研讀批改《玉茗堂四夢》的內容中發現，晉叔在戲劇理論的發表上，亦有其獨到的見解。尤其是他對「戲曲當行」一詞涵義的闡述，繼承了前人優秀的見解，並且發人所未發，他所謂的「當行」，非僅就作者而論，更涉及演員的問題，對於後代曲壇的影響，不容小覷。故本文擬以「臧懋循之戲曲當行論」為題，觀察他在相關文章及《玉茗堂四夢》的批評中所觸及的戲劇理念，其中包含了歷來戲劇理論中所討論的語言、曲律、關目、人物、腳色、曲牌及其他舞台演出等各個層面的相關問題，對後來戲劇理論的發展，具有深遠的影響。故知臧懋循的「當行論」，在劇壇上有其重要地位，是為中國戲劇理論史上，不可忽視的一頁。

Tsang Mao-hsun was an important critic on drama in Ming Dyn. But the only thing that everybody praises was his achievements on editing “The selections of Yuarn drama” and its supplement. It does not know thoroughly for Tsang Mao-hsun. One idea came to me when I was reading the Tsang Mao-hsun’s revision of “Yu ming-tang’s four dreams”, that was his comments on drama are special. What particulars were his theories of “be expert at drama”. They were complete and strict. Have a great influence on drama in later generations that we must regard seriously. I taking “Tsang Mao-hsun ‘s theories of ‘be expert at drama’” for the title of this paper. To research the theories in his articles. Including the words,the tonalities,the structure,the characters,the actors,the songs, and the considerations on performance. They almost contained all the dramatic theories. The influence of his theories was profound and lasting on drama in after years. So we know that Tsang Mao-hsun’s criticism of “be expert at drama” is carrying on the past heritage and opening up the future. It is an important page that can’t be ignored in the history of Chinese traditional opera.