Critical discourse analysis has become a new branch in linguistics. Nevertheless, up till now, the definition of discourse analysis, discipline task and its purpose are still ambiguous. The paper starts from the introspection of critical discourse analysis and active discourse analysis and stipulates the following points: ( 1 ) Discourse, opposite language, is an ontological category. (2) Its existing forms are written texts and oral discourse. (3) Due to different research purposes, discourse analysis belongs to sociology, philosophy of...