Abstract: Bill Nichols puts forward a concept of "voice" as the primary principle of documentaries, according to which he divides documentaries into six categories. However, in his classification, the concept of "voice" is shifted from content to form, making some of his classification contradictory to his idea that documentaries should deal with real people and the real world. In addition, Bill Nichols' criticism of traditional documentary types on the ground of ethics is not reasonable, because documentary ethics is merely related to personal operation and has nothing to do with the classification of documentary. In the two editions of his Introduction to Documentary, Bill Nichols shows his lack of logical thinking about documentary ontology and classification theory, so that we need reflective thinking and independent judgment on his theory.

Key words: documentaries, documentary classification, Bill Nichols, “voice”