The main feature of a system includes the element, structure and function. Accordingly, the internal and external elements of CER are important components of CER system. The internal elements refer to the social and natural capital, such as the resources, staff, technology, products and waste, etc. The external elements refer to the investors, community, partners, government, customers and other stakeholders. CER can be classified into four levels of economy, law, ethics and beneficence, in light of the pyramid structure of CSR. Each level has its unique function. In the first place, enterprises directly taking environmental responsibility can help reduce social cost and increase social resources allocation efficiency in the long run. In the second place, the legal CER can regulate the company to externalize the environmental cost. In the third place, the ethical CER can ensure the harmonious and just relationship between human being and natural environment. In the fourth place, the charity act of CER can improve the business reputation and credibility and creates a real impact on the social themes of the local communities. In light of SDS, the four levels of CER—economic level, legal level, ethical level and philanthropic level—make progressive development from basic class to advanced class. The capabilities of CER will also continue to upgrade and extend. When companies practice CER, they must recognize the objective relationship between nature and human society and perform well with the four principles of dependence, coordination, symbiosis and sustainability.