Ecological civilization construction has become the conscious practice to build the present Socialism with Chinese Characteristics. The conscious practice comes from the conscious theory. It is the theoretical foundation of the ecological civilization construction to understand the relationship between man and nature of Marxism. In Marxist view, man and nature are unified intrinsically, and mutually constitutive, therefore, they must develop harmoniously. That is to say, man must respect nature, conform to nature, protect nature in the process of practice, in order to construct ecological civilization.