Fraternity means kindness and being friendly, which is an important moral quality of human being. Fraternity not only can lubricate interpersonal relationship, but also is an indispensable moral foundation in the construction of ecologically harmonious society because of its rich ecological connotation. In the perspective of individuals, fraternity is the moral foundation in constructing an ecologically harmonious society. In the perspective of the society, fraternity is conducive to the formation of the community of common ecological destiny for all mankind. Constructing an ecologically harmonious society can benefit from the generic attribute as well as group and individual attribute. The whole society should reach ecological consensus, countries are supposed to promote the cultivation of ecological fraternity, and individuals should be consciously friendly to the environment and have belief in environmental virtues.