This article aims to interpret the green thoughts in Habermas's works. In the framework of postmetaphysical thinking, there are embedded in a naturalistic philosophy in Habermas's theories, which we call "Green Habermas." In the context of this article, it refers to enlightenment rationality of the relationships between "human being and nature," but Habermas criticizes scientism and its technology. To stress the importance of naturalism, Habermas distinguishes into two naturalism: soft and hard. And he advocates a nonscientistic or "soft" naturalism. On the interpretation of soft naturalism, we finally investigate his ethical arguments against genetic engineering to elaborate the basic discourses of "Green Habermas."