Free indirect speech is an important mode of discourse, which is widely used in literary works as a rhetorical device as well as a syntactic method. Free indirect speech is a typical representative of double-voicedness, and a discourse narrating mode encompassing author, narrator and subjective consciousness of the characters. Scholars have conducted researches on it for a long time. This paper conducts a review on the free indirect speech by scholars at home and abroad, aiming to bring some enlightenment for future studies.