The concept of relevance has played a major role in information retrieval(IR)research since the 1950s. The goal of an IR system is to provide users with access to〝relevant〞documents. Therefore this paper re-examines the viewpoints of majors writers in the field, then introduces a new approach. It includes definition、importance、five approaches(the system-oriented approaches、the user-oriented approaches、the multidimensional approaches、the cognitive approaches、the user-centric approaches)and the future development.