Two kinds of essay, prefaces and letters, embody Yuan Xiaoxiu's theories on literature. In this regard, we have found eight principles as a result of our research, which are as follows: ”Respect of the natural spirit,” ”Use of meaning to control the method,” ”Not giving up on the format,” ”Valuing rhyme to achieve an amusing effect,” ”Emphasis on implied meaning,” ”Maintaining a plain style,” ”Reading extensively for all kinds of knowledge,” and ”Going extreme in technique.” All his opinions on writing have been realized and proven in his own literary works.