This paper aims to introduce the contours of radical orthodoxy, with a critical response to its ideas. It has three parts. The first part answers the question: Who are the members of radical orthodoxy? It concludes that although there have been many supporters of radical orthodoxy, the editors of the Radical Orthodoxy series (John Milbank, Graham Ward and Catherine Pickstock) can be identified as its key members. This conclusion also determines the approach of the study to radical orthodoxy in this paper. The second part examines the main themes of radical orthodoxy, such as the concepts of "radical", "orthodoxy", theology of participation and so on. In addition, it traces the roots of radical-orthodox understanding of the modem and the postmodem, especially in the thought of John Milbank. The final part gives a critical assessment of some ideas in radical orthodoxy and proposes in what direction they can be further developed.