As there were lacks of historical documentation, similarities shared by ancient Sushen and Dong Hu languages, which are ancestor language of Manchu and Mongolian respectively, are difficult to trace. However, the later documents left by Jurchen and Mongolian and studies of Chinese northern tribal histories revealed the contacts as well as cross-influences between Jurchen and Mongolian languages. This paper tends to explore the components transcribed in Chinese characters for ancient Mongolian and ancient Manchu languages, documented in The Secret History of Mongolia and Jurchen Vocabulary Translation, so as to show a more objective history and process of Manchu-Mongolian language contacts and inter-borrowings.