明清戲曲文獻中不乏對於南北曲異同之論述，本文從二十五家說法中歸結出：北曲乃因「莽爽之氣」而以「豪辣灝爛」為本色；南曲乃因「姿韻婉媚」而以「清新韶秀」為天然。北曲的語言特色細繹之有四個特點：成語的引用、疊字的繁富、狀詞的奇絕、經史詩詞的引用。而南曲可從元人高明《琵琶記》、明人湯顯祖《牡丹亭》和清人洪昇《長生殿》三部代表性鉅製來觀察其語言文字之較諸北曲雜劇之異同，明顯的有以下現象：其一，襯字較北曲少；其二，疊字衍聲複詞、狀聲詞和成語等不如北曲使用頻繁；其三，歷經明代「文士化」的作品，其佳者近於詞而優雅，其劣者乃濃艷而板滯；與北曲之或多用白描口語而有莽爽之致，或多用麗詞雅語而不失清剛之氣，形成成南北絕然之異趣殊途。

There are numerous discourses on the differences and similarities between the Northern Tune and the Southern Tune, in the archives of traditional operas of Ming and Qing dynasties. In this article, I will summarize the arguments from twenty five critique works, and make the following contention : the Northern Tune, originated from a natural and wild environment, is known for its heroic and grandiose style, whilst the Southern Tune, out of a more temperate and mild surroundings, is celebrated for its guilelessness and gentleness. There are four characteristics in the language of the Northern Tune : the use of idioms, the lavish repetition of laminar words, the superb decorative expressions, and the quotation of classics. On the other hand, from the masterpieces of Southern Tune : 《The Legend of Lute》by Gao Ming of Yuan Dynasty, 《The Peony Pavilion》by Tang Shian Tzu of Ming Dynasty, 《The Palace of Eternality》by Hong Sheng of Qing Dynasty, we can further identify the differences and similarities between the Southern Tune and its northern counterpart. First, there is less word inserting in the Southern Tune. Second, there is less use of laminar wording, sound-duplication words, onomatopoeia, and idioms as well. Third, after the literary innovation of the Southern Tune in Ming Dynasty, the better works would reach the level of the best poetry, while the lesser ones would seem flashy but dull, while the language of the Northern Tune would either be vernacular and natural, or graceful without losing the heroic sense. As a result, the Northern and Southern Tunes take on different savors and routes of progress.