Sustainability is a current global issue. Companies have published CSR (corporate social responsibility) reports to disclose sustainable performances and actions in economic, environmental, and social aspects. In Taiwan, the qualified listed companies including developers have been required to compile CSR reports since 2014. However, literature points out that the disclosure and quality of CSR reports are not adequate. The objective of this research was to examine the environmental contents of CSR reports. Based on the 2016 GRI (Global Reporting Initiative) Standards, this study analyzed the disclosure levels and quality compliance degree of the 30 environmental indicators and the relationship between the two. Six listed developers with the largest revenues were chosen as cases to study. The results show that the disclosure levels of environmental indicators were not high and the disclosure levels and numbers of environmental indicators were not consistent. In the quality principles, timeliness is the most compliant one but reliability is the last. The disclosure levels and quality compliance show a low positive relationship. Based on the requirements of GRI Standards, developers can establish their own environmental management approaches, which can help raise both disclosure levels and quality of the reports. Further, a CSR report with external assurance can strengthen its reliability, increase public trust and meet the government policy.