The desulfurization and denitrification project of Shenmu Xinyuan Comprehensive Utilization Power Generation Co., Ltd. contracted by our company has passed the environmental protection acceptance at one time. In this project, the original SCR system was transformed into an SCR+SNCR system, and the original ammonia desulfurization system was transformed into a calcium desulfurization system, so as to maximize the use of the original equipment for transformation. The flue gas volume of the project is 200000Nm3/h, the SO2 concentration is 1000mg/m3, the measured value of SO2 concentration in the flue gas after treatment is <50mg/m3, the measured value of particulate matter is <10mg/m3, and the measured value of nitrogen oxide concentration is <50mg/m3. Since the commissioning and operation, the system has reached the standard stably and achieved ultra-low emissions, which has been highly praised by customers.