Historically, Korean and Chinese diplomatic documents were originally written in Muneonmun, a pure Chinese writing style, but since the Yuan Dynasty in China, Imun began to be used in official writing style. As this style was very different from the traditional Chinese writing style, Korea needed Korea needed professional talent to carry out tasks in this field and a series of measures had to be prepared in order to cultivate such talent. In the early Koryo Dynasty, Ihakdogam was established and Imun had been taught with Ihakgyogwan in Sayeokwon. Even at the time of the Choson Dynasty, Imun had been taught in Sayeokwon or Seungmunwon. During the Choson Dynasty, while a set of reference materials for the preparation of bilateral diplomacy documents were compiled by the government as well, documents are mainly diplomatic documents between Choson and Ming or Qing Dynasty. And Chwijaeseo had been designated by the government in order to select dedicated talents for Imun. This study reviewed the types of Chwijaeseo which was used in such Korean-Chinese diplomatic documents and selecting talents for Imun and the linguistic characteristics of Imun based on Imunjimnam. According to this review, although the official form of the so-called 文 文, used in the diplomatic documents of Korea and China, is based on Muneonmun which is traditional Chinese writing style, complex and various chracteristics in terms of vocabulary and grammar are observed. First of all, while a lot of expressions that were commonly used in official writing style were used and the expressions reflecting colloquialism at the time with modern era Chinese and modern Baaekhwamun were used, these forms cannot be found in Muneonmun. Also, many expressions of so-called Yuan Dynasty era Chinese that was influenced by Mongolian langugage or used only in the Yuan Dynasty can be found. Therefore, it can be seen that Imun is a difficult writing style to learn unless going through a dedicated learning process even if being proficient in the traditional Chinese writing style. Therefore, In the early Choson Dynasty, a professional education institution such as Ihakdogam was established to teach Imun and Hanigwa was established to select talents for Imun through a rigorous testing system so that a smooth diplomatic exchange with China was prepared.