Text understanding is an important research branch in artificial intelligence,which avails the effective interaction between human and computer with natural language.Text feature extraction is one of the basic and key steps for computers to understand and perceive the textual data.In this paper,we introduce the development history of text feature extraction and the mainstream feature extraction methods in recent years,and prospects the future research directions of text feature extraction.The three semantic hierarchies,namely word representation,sentence representation and discourse relationship mining are elaborated,then a case is given to show the typical application of text feature extraction on question answering system.