从古代汉语到现代汉语，出现过“亦”和“也”两个本义表示类同的副词，两者各自生成了自己的语义网络，同时又存在着交叉以及历时替换的关系。本文以这两个副词为研究对象，主要完成了以下工作：第一，对副词“亦”和“也”的各种义位进行分类，主要分为表示类同的“亦1/也1”、表示极性衍推的“亦2/也2”、表示语气的“亦3/也3”，在其内部又各自划分了一些次类。第二，在大量历时语料的基础上，对两者在历时平面上进行全面的考察，用统计的方法对不同历史时期“亦”和“也”的分布情况做出描写和分析。第三，对“也”逐步替代“亦”的过程予以描写。阐明现代汉语中用法复杂多样的副词“也”的各个义位和用法在历史上出现的年代及先后顺序。第四，在描写的基础上，试着建立各义位之间的内在联系，找出各义位之间的语义虚化链，并揭示其语义逐步虚化的动因和机制。两者都是由表示类同的客观意义引申出带有强调色彩的极性衍推义，类同义还引申出了各种表示语气的用法。

‘Yi’ and ‘ye’ exist both in ancient Chinese and modern Chinese as two adverbs signifying sameness. These two adverbs have formed their separate semantic network, but at the same time, they are of an alternative and diachronically replaceable relationship. Focusing on the two adverbs, this paper has completed the following tasks:First, classify the various meanings of ‘yi’ and ‘ye’ and divide them into three major semantic categories: ‘yi1’ /’ye1’, signifying sameness, ‘yi2’ /’ye2’, entailment and ‘yi3’ /’ye3’, signifying mood, then under each category, smaller subcategories are further divided.Secondly, based on the analysis of large amount of corpora, this paper has a thorough research on both ‘yi’ and ‘ye’ diachronically and analyzed their frequencies in different historical period.Thirdly, this paper has described the process of ‘ye’ gradually replaced ‘yi’ and expounded the sequence of the different semantic meanings of ‘ye’ in history.Fourthly, this paper, on a description base, has attempted to establish the inner relationships of the different semantic meanings and found out the grammaticalization chains between the different semantic meanings, so as to indicate the motivation and mechanism of the gradual grammaticalization.