This paper briefly describes the concept of bi-directional DC/DC converter. It introduces the bi-directional DC/DC converter category, control technology and practical application. Bi-directional DC/DC converter is a vital component of the power electronic converter. In the case of two-way need energy flow, bi-directional DC/DC converter has important application value. As the development of science and technology and production, the bidirectional converter transformer research will enter a new stage.