the existing "The secret history of Mongolia" is spelled by the Chinese characters. This paper discussed the function word meanings, that with both grammatical and lexical meanings. Based on this, we explain the function word meaning of "the secret history of Mongolia".

The full text contains the introduction, chapter one, chapter two .

The introduction include the research purpose, research significance, research methods, research situation as well as needs the main source.

First chapter, simple introduced the academic experts researches about Mongolian function word significance of the modern Mongolian and the intermediate stage. From this analysis, we redefined the function word significance and conclude the function word has both the grammatical and lexical meanings. The second, the paper explained the standard of lexical category division and present the standard of this paper, and has divided the function word with six big kinds(postposition, expression word, conjunction, interjection, adverb, additional word) and multi-category words, then has carried on a slighter division.

Second chapter, has counted function word of "The secret history of Mongolia" and made the system classification, then explained these function word significance.