Abstract: The current domestic and foreign systems of effluent permit limits andpollutant reduction technology assessment were summarized. The framework and feature of the USA and EU systems were introduced in detail, which were worth learning for China. Based on the principle of “by region, by type, by grade and by term", the system of effluent permit limits and pollutant reduction technology assessment in control unit was constructed. The connotation and characteristic of this system were illuminated. The technology assessment and best available technologies of various pollution sources, the indexes, methods and procedure of technology assessment, the technology verification platform, and the determination of effluent permit limits were discussed.