Shenhua Guohua Zhoushan power plant unit 4, as one supercritical power unit, had advanced environmental protection auxiliary project, including Denox system, SWFGD system and etc. The unit 4 has been officially put into business operation after it completed the test run of 168 hours. During the test run, Zhejiang province environmental monitoring center station took samples on site, and the final test result showed that the SO₂ emission concentration was 2.86mg/Nm3.