There are a number of important variant Characters in the editions of Chengjia and Chengyi of Dream in the Red Mansions. Compared with them, tracing the synchronic description and diachronic development of the form and meaning of words, this study concludes that Chengjia version trends to use old words, south words and written words, while Chengyi version shows the opposite characteristics. This study can provide proof their language foundation for the two versions from the perspective of lexicology.