Abstract: There were two major ways to deliver personal letters in Song dynasty, by official or civil. The latter one can be divided into two ways: passing through someone, i.e., special messenger, or asking other people to transfer the letters. This paper is trying to use the case of the letters between Zhu Xi and the officials, friends, students and others to discuss the influence and defects of the way the letters being delivered according to the above mentioned three ways. Besides, the paper also tries to figure out the cost of time of delivering letters and the problems of leaking privacy.

Key words: Song Dynasty, Zhu Xi, delivering letters, time consumption