Abstract:As a special type of documentary, Sci-Fi documentaries can be further divided into three types: documentary of Sci-Fi theme, documentary of Sci-Fi style, and documentary with Sci-Fi elements. All the different types have common characteristics in narration: possible world and future tense in narration, by which Sci-Fi can be documentary and the value of scientific and humanism, by which Sci-Fi documentaries can be educational.