Through specific examples, we can discover that ancient official documents require accurate words on the text and object to excessive rhetorics and classical allusion. It puts emphasis on keeping the writing process and contents secret, and making a point lofty with reality, which are the same as the requirements of the modern official documents. However, there are also some principles that are not required in the modern official documents. For example, writing process should be fast and fine;writing subject should adhere to the truth.