With this essay, the author, Professor Wang Wensheng has given a study in the earliest outline of Chinese literary thought--"Poetry Expresses Intent"--on several main respects: 1, He has defined clearly the subject and reviewed the historical and present situations as well as purposes and methodologies which Chinese and Western scholars adopted in this field; 2, Through rigorous textual research, he has discovered for the first time that the outline of "Poetry Expresses Intent" came into existence in the middle of 9th century B.C., which proves that the outline of "Poetry Expresses Intent" is not only the earliest literary thought existent in China but also the earliest one known in the world; 3, In theory, he has elucidated that the outline of "Poetry Expresses Intent" is a poetic outline of expressive theory that poetry trances emotion; 4, By a general comparison of literary thought between China and the West, he has expounded the traits and influences of the outline of "Poetry Expresses Intent."