Objective: The paper is to study the sewage treatment degradation thermal energy management system of a sewage treatment plant, to achieve the energy saving and emission reduction. Methods: This paper studies the electron equivalent reaction of biochemical reaction of organic matter. Under the environmental conditions of biochemical degradation of sewage, biochemical oxygen demand (BOD5) is used to indicate the amount of heat generated by the degradation of organic matter in sewage. The paper designs a management system based on sewage heat recovery, and uses it to carry out heat recovery of sewage. Also, the energy-saving benefits produced by the heat management system are studied. Results: The sewage heat recovery system is more energy-efficient than the common air-conditioning supply system. In the use of sewage heat management system for one year, it achieves energy saving of 30.4% better than that of ordinary air-conditioning systems. The system for one year saves electric energy of 2145464 kWh, which is equivalent to saving 2511994⋅104 kJ primary energy. This system saves 858.2 tons per year of standard coal, reduces CO2 emissions by 2789.1 tons per year, reduces SO2 emissions by 19.61 tons per year, reduces NO2 emissions by 7.12 tons per year, reduces ash emissions by 135.19 tons per year, and saves tap water replenishment 40243 tons per year. Conclusion: The sewage thermal energy management system can utilize the thermal energy in the sewage, thereby using the sewage as a new clean energy. It can effectively improve China’s current energy shortage and make a substantial contribution China’s energy saving and emission reduction goals.