Written Manchu in Qing Dynasty had a great influence on written Mongolian in Mongolian people’s education, and writing learning. Firstly, in Qing Dynasty, besides going to Mongolian official schools especially set up for Mongolian Eight Banners, children of these Mongolian Banners also went to Manchu educational institutions for written Manchu learning for the future ascending into the ruling class after taking examinations of Manchu rulers. Thus, written Manchu learning had become the most important task for Mongolians in Qing Dynasty. Secondly, in Qing Dynasty the Mongolian literate people, when actively learning written Manchu, started to use Manchu letters to mark the sound of Mongolian language. As a result, in Qing Dynasty as well as Min Guo time, written Mongolian with Manchu transcription of sounds became a very popular trend, such as there were “Mongolian borrowings written in Manchu”, “Manchu transcribing of Mongolian sounds” and “mixed written Manchu and Mongolian ways in writing”. Besides that, in the process of using written Manchu to mark the Mongolian sounds, written Manchu shed influences to Mongolian letters resulting in the infiltration of Manchu way of writing to that of Mongolian. In Qing Dynasty, influenced by written Manchu, Mongolian letters used to transcribe loan words took many Manchu ways as a reference, or Mongolian people directly used Manchu letters in transcribing Chinese loan words or they added special spelling way to transcribe other loan words.