「幼曲」，或寫作「細曲」，又稱為「崑腔」。其內容主要是崑曲及明清以來流傳的小曲。小曲的旋律細膩委婉，風格近崑腔，因此民間藝人混稱為崑腔。本論文主要討論幼曲【小牌】與明清小曲的關係及【大牌】與崑曲的關係。【小牌】常用曲牌，以【碧波玉】、【桐聲歌】、【雙疊翠】三牌聯套為最多。本文舉明清小曲的相關資料，尤其清初曲集《萬花小曲》、日本波多野太郎家藏曲譜《清樂曲牌雅譜》與台灣幼曲相比對，以論證台灣幼曲與明清小曲的關係。幼曲【大牌】，是一個曲牌，還是許多曲牌的聯綴？它的來源是什麼？過去似未有人探討過。本文以幼曲曲集《典型俱在》大牌四十套，與崑曲譜做比對，發現有二十三套的曲文與崑曲譜相同或相近似。本文並以〈追韓〉、〈店會〉、〈六月飛霜〉三套曲的幼曲曲文與崑曲譜曲文製表對照，論述大牌與崑曲的關係。

“You qu” (tender songs), or written as “Xi qu” (refined songs), also known as Kun tunes mainly encompasses songs of Kun Opera and popular songs during the Ming and Qing times. The delicate circumflex tones of You qu is so close to Kun Tunes that some folk musicians confuse it with Kun Opera. This article intends to clarify relations between the “minor songs” of You qu and the Ming and Qing folksongs, and the “major songs” and Kun Opera. Among the “minor songs”, the most common used song set is “Bipoyu”, “Tongsheng ge”, and “Suangdiecui”. By comparing You qu collections in Taiwan with sources provided in this article, especially the early Qing collection Wanhua xiaoqu and 波多野太郎’s collection scores Qingyue qupai yapu, I would like to demonstrate the connection of You qu in Taiwan and folksongs in the Ming and Qing times. Whether the “major song” of You qu is a song or a song set? What is its origin? Apparently these subjects remain untouched. According to careful examination of 40 sets of the “major songs” in Dianxin juzai and scores of Kun Opera, 23 song sets of You qu are similar, if not the same, to Kun Tunes. Moreover, a table that contrasts song sets “Zui Han”, “Dian hui”, and “Liuyue feishuang” with the scores and libretto of Kun Tunes will be helpful to explain the relations between the “major songs” and Kun Tunes.