Combining with the history of ancient Uygur, this thesis discusses the lexical development and diversification of the ancient Uygur document language from three aspects, that is, the richness of the vocabulary and the complication of vocabulary structure, the influence of foreign culture and the vocabulary borrowing from other languages.

It has been one of the most important Old Uygur texts which were unearthed in Xinjiang since the 20~(th) century.

This article classifies the phonetics harmony of the ancient Uygur document language into 3 types--vowel harmony, consonant harmony and vowel-consonant harmony.

Based on the previous studies and the investigation of the document language materials and live materials of the modern Turkic languages,the article proves that there exists no short vowel e.

In this paper the author makes a study of auxiliary word in Huihe literature language in Gaochang area from ninth to fourteenth century and proposes the standard of identifying auxiliary word.

This article conducts a survey of the Ph ags-pa Script used by ancient Uighur people in the Yuan dynasty according to some unearthed Ph ags-pa Script which recorded ancient Uighur language both on stamps and in literature .