Dialects are living fossils of language evolution.Dialects in a region accumulate languages of different historical pe-riods,and some words in each language are preserved from ancient Chinese.Datong dialect retains a large number of ancient words,which reflects the long history and culture of Datong.Based on this understanding,five ancient dialect words are analyzed and eluci-dated including Ji,Nongdai,Yangji,Yeyi and Cao,and the textual research is carried on with the help of reference books and ancient books in order to provide materials for the study of the dialect.