本文針對前輩學者對徐大椿(約1693－1771，字靈胎，號洄溪，江蘇吳江人)《樂府傳聲》（成書於乾隆九年，1744，刊於乾隆十三年，1748）的研究之異說進行釐清，以求全面掌握徐氏曲唱體系之精粹，揭示其論之美學意涵，以明其在曲唱理論史上的地位。其曲唱體系之三大主軸為：（一）以「文樂相諧以傳情」的「存調」目的為指導原則，確立「唱作相謀」的曲唱理論基礎。（二）以「字－句－牌－調－情」建構曲唱之完整呈現曲體的歷程。（三）以「口法」為演唱方法之具體內容，以「心、力、氣、位、形、聲」為口法操作六要素，建構「以心領口」、「以形統綱」兩大原則。其理論貢獻有三：（一）此三大主軸的交織、互動與協調，使曲唱理論突破魏良輔以來「字清、腔純、板正」的平面格局，成為一縝密而通達的立體化模式。（二）將沈寵綏「切法即唱法」的曲唱聲韻學轉為真正的唱曲之學，完成演唱字腔中各種層面的建構。（三）發明「口法」理論，辨析精密，論述具體，乾嘉傳統崑唱理論至其手中才算真正完成建構，直至近代俞振飛承其父俞粟廬而提出的「字、音、氣、節、情」，皆不出徐氏建構的基模。

In this paper, it clarifies different study theories for Yuefu Chuansheng, by a senior scholar Xu Dachun, to grasp the quintessence of Xu’s melody singing system, uncover the aesthetic implications of the theory and make clear for its position on melody singing theory history. The melody singing system mainly includes three main lines: (1)It takes “Melody Saving” as purpose of “to express tender feeling with the harmony of both article and melody ”as its guiding principle and establishes the melody singing theory basis of “singing and writing are working together”; (2) It takes the melody singing structure of “word-sentence-name-tune-feeling” to present the course of melody completely; (3) It takes “oral method” as the detailed content of singing method, and “ heart, force, breath, position, shape and sound” as the six elements of oral operation to construct two principles of “leading oral singing with the heart” and “unifying the principle with the shape”. The theory has three kinds of contribution: (1) The interweaving, interaction and coordination of the three main lines make planar pattern of “clear words, pure tune and correct rhythm” broken through since Wei Liangfu and become a meticulous and understanding stereo mode; (2) It transfers the rhyme singing method “way of cutting is the way of singing” by Shen Chongsui into real melody singing and completes the structure at all levels in words and tune singing; (3) It invents “oral method” theory, which is analyzed precisely and discussed in detail. Traditional Kunqu Opera singing theory of Qianlong and Jiaqing eras is constructed completely in Xu’s hands, and the “word, sound, breath, rhythm and feeling” theory proposed by Yu Zhenfei inheriting his father Yu Suying’s theory in moredern times is still all developed from the basic mode of Xu’s structure.