「文律論」分別指語言修辭論和音韻格律論。周德清《中原音韻》是為北曲編撰的著作，本文從撰寫《中原音韻》的背景切入論題，進而探討文與律兩大內容及其相互涵容的關係；最後說明文律雙美成為元明之際戲曲品評的美學觀點。 周德清的音韻格律論包括「明腔、識譜、審音」三方面，其中「襯字、對耦、末句、務頭、陰陽」等創作法則，表面上屬音韻格律，但每一項都不離語言修辭；相對的，論造語藝術亦不離格律技巧。換言之，在音韻格律中經營語、意俱高而且文俗相濟的俊語熟字;在語言文詞中鋒鍊韻協音調的北曲文體。周德清的文與律互相涵容，而其建構的文律雙美，成為元末明初重要的創作理論和鑑賞觀點，他是第一個建構北曲文律論的曲學家。

This article deals with the background of the Zhongyuan yinyun 中原音韻, a book compiled by Zhou Deqing 周德清 specifically for use with northern sanqu 散曲 and zaju 雜劇, its content and the close relationship between rules for language and prosody, and finally with the development of the principle “embellishment of language and perfection of prosodic rules” (wen lü shuang mei 文律雙美) as a major aesthetic criterion for northem sanqu and zaju during the Yuan and Ming dynasties. Zhou’s theory of prosodic rules consists of three parts: “differentiating musical tunes” (mingqiang 明腔), “identifying musical scores” (shipu 識譜) and “discerning musical tones” (shenyin 審音). On the surface, some of the creative principles, such as “supplemented words” (chenzi 襯字), “antitheses” (duiou 對耦), “end sentences” (moju 末句), “key points” (wutou 務頭) and “first and second tones” (yinyang 陰陽), fall under the rubric of prosodic rules. Nonetheless, prosodic rules cannot be separated from the embellishment of language, just as the embellishment of language relies on prosodic rules. In other words, in Zhou’ s view extremely meaningful and beautiful language should be prosodically regulated at the same time that prosodic rules are to be tempered by the art of language. Zhou’s inter1inking of the art of language and prosodic rules unites these two elements and became the most important creative theory and appreciative criteria in the late Yuan and early Ming. He was the first theorist to formulate a theory of language and prosodic rules for northern sanqu and zaju.