本文透過出土文獻的通假字與傳世詩歌押韻相互參證'並借助歷史比較法的層次分析來研院漢語的上古音韻。漢語音韻史的研院，特別在古韻部系統的分布不平衡、上古元音的數量與元音圖上所呈現的類型、音值的構擬、合韻、跨韻部通假、韻尾是劉七......等問題上，一直存在較多的爭議。郭店與上博楚簡諸篇的通假字，反映了我們在以往的研軒究中也發現的問題，如跨韻部的通嗨，在陰聲韻部可見之幽、之魚、之脂、之歌、脂魚、脂微、脂歌、支歌、侯魚、幽侯等通假字例;陽聲韻部有真文、文元、真元、耕真、歌元、侵談、冬東、冬侵......等現象。這些紛繁的異部通假現象，也出現在先秦兩漠的詩歌合韻，既有的上古音系架構無法解釋它們頻繁接觸的語音基礎。研究楚簡通假字，有助於檢測上古音系的擬測，亦有利於上古音的分時、分域研究，開展漢語方言史。除去幽、宵、侯、魚四部，本文探討其餘陰聲韻部的通假關係，而楚簡諸篇通假字的聲母、陽聲韻部亦將另文討論。本文主要的車詰命是:異部通假與合韻應以層次異讀來解釋，一個音讀層次可能反映或時代、或地域、或演變類型的因素。從異部通假與合韻來看，上古之、脂、支韻部應有一個低元音的音讀層次，不限於楚地;脂、微韻部的關係有別於前輩學者所提的先秦分、兩漢合之說;發生在通假或合韻的陰陽罣揮專現象，陽聲韻部讀鼻化韻，入聲韻部讀喉塞韻，是有別於鼻尾韻、塞尾韻的另一個音讀層次;楚地的祭部應已獨立;魚、都重假反映較早的低元音層次格局。

This paper investigates the interchangeable characters in certain Chu bamboo slips ofGuodian and Shangbo. This paper shows that a study ofthe interchangeable characters in these texts can help to solve some long-stand ing problems concerning the interchangeability of characters and rhyme merger. This paper will specifically discuss the interchangeability of charac ters from the vowel/stop-ended rhyme division except the divisions of you , xiao , hou , and yu. The primary conclusion of this paper is that the interchangeability of different divisions and rhyme merger are the result of convergence of readings from different strata. The interchangeability of different divisions and rhyme merger indicates that the rhyme divisions zhi (之)， zhi ( 脂)， and zhi ( 支) should have a low vowel stratum. The switch of the vowel/stop-ended rhymes and the nasal-ended rhymes that occurs in the interchangeable characters and rhyme merger arises from a different reading stratum. The ji ( 祭) division should have been an independent division. The interchangeability of yu ( 魚)andge( 歌) reflects an earlier low vowel stratum.