According to American scholar Bill Nichols, documentaries can be divided into ().

According to American scholar Bill Nickalls, documentaries can be divided into the following six categories: ① Poetic documentaries. Poetic documentaries appeared in the 1920s. As a representative of Rain in Evans, this type of documentary does not emphasize narrative, creation of specific time and space, or coherent editing. It focuses on the creation of rhythm and the juxtaposition of different spaces, with the aim of conveying emotions and emotional appeal. ② Descriptive documentary. Explanatory documentaries also appeared in the 1920s. The propaganda intention of this documentary is very clear, and the creator relies on the power of explanation to convince the audience to accept his own views. The typical features in form are "Voice of God" evidence editing and omniscient viewpoint. ③ Observe the documentary. Observation documentary appeared in the 1960s, and its technical basis lies in the appearance of portable cameras and tape cameras. This kind of documentary gives up understanding and acting, and the documentary director becomes a "fly on the wall". ④ Participatory documentary. Participatory documentaries appeared in the 1960s. The representative work is The Chronicle of Summer by Rush and Edgar Moline, which does not conceal the director's presence, but deliberately emphasizes the interaction between the director and the subject. ⑤ Reflect on documentaries. Reflective documentaries appeared in the 1980s. The representative work of this kind of documentary, Yueming Man's Surname, is a reflection on the social and historical process presented by the documentary. Like other types of documentaries, reflective documentaries attach importance to the expression of the real world, but more importantly, the director also expresses his reflection on the documentary creation itself. This kind of film is often abstract and difficult to understand. ⑥ Presentation of behavioral documentaries. Documentaries that express behavior subjectively magnify real events and deviate from the realistic style. Emphasize the subjective expression of the creator. Masterpieces like Marlon Riggs's "Tongue Without Knot" are often very close to avant-garde movies.