Reflecting some significant differences in the dictionaries on the two sides of the Taiwan Strait through the process of distinguishing and analyzing common four-character idioms, this study mainly discusses the heteromorphic phenomenon of the idioms. The research method is to conduct research on the corpus of ancient and modern materials to understand ancient and modern usage of similar idioms. This study lists out eight groups of common idiom variants as examples. It intends to explore the reasons for the formation of individual vocabulary from the perspective of literary theory supplemented by the data content of the classical literature database and modern corpus to show the ancient documents and the modern people’s language use habit. At the same time, it compares similarities and differences between Taiwan’s Mandarin Dictionary (Revised Edition) and the Chinese Dictionary in Mainland China, comparing once again different aspects of the dictionary compilation and basic language education. It also shows the difference between both sides of the Taiwan Strait in the aspects of idiom variants included in dictionaries and the principle of word inclusion in them.

Spoken words tends to be verbal communication, because the source of the words is different, or for use in different groups, it produced the sound homophones nearly glyph (written symbols) through the synchronical and diachronical spread, which is a spoken word may become phonetic variations occurred in the communication process, and lead to produce multiple variants including the shape of words and the numerous, complicated and changeful usage of words, sometimes even cover up their original real feature. This article focuses on spoken word about the same word but variant character of the oral literature (including abroad), which reflected Beijing dialect in the late Qing and early republic period