After nearly forty years of development, China has established a preliminary regulatory system for fixed pollution sources with the pollutant discharge permit system as its core. From the perspective of institutional characteristics, the pollutant discharge permit, as an administrative permit, is one of the administrative management tools for national pollution control. It focuses on fixed pollution sources as the control object and is based on total pollutant control. Meanwhile, the pollutant discharge permit is a valuable concession that can be traded through the market. From the perspective of institutional functions, the pollutant discharge permit maintains the order of environmental utilization and protection by controlling the pollutant discharge behavior and emissions of polluters. In addition, the pollutant discharge permit, as an environmental "compliance contract" for enterprises, is also an important basis for identifying illegal pollutant discharge behavior. In the current context of the compilation of the Ecological Environment Code, the pollutant discharge permit system will be systematically regulated in the pollution prevention and control section of the Ecological Environment Code. In the future, it is necessary to further achieve the orderly connection between the pollutant discharge permit and the environmental impact assessment system, and to include carbon emissions and other factors in the pollutant discharge permit management in accordance with the law, implement full factor management, and promote the comprehensive implementation of the pollutant discharge permit system. Keywords: Pollutant discharge permit. Pollutant discharge permit. Reform of pollutant discharge permit system. "One certificate" supervision.