This research conducts a series of industrial tests on coal reburning of a 600 MW pulverized coal boiler firing lignite, which is one part of a coal reburning demonstration project. When running steadily under 600MW load, the boiler has an average NOx emission of 274 mg/m3 (O2 content in flue gas is converted to 6%), the NOx emission is reduced by 65.36%. In the meanwhile, loss of ignition (LOI) under coal reburning rarely increases. Three operation conditions - traditional air feeding, air staging and coal reburning - are realized, respectively, during the industrial tests, and the results indicate that coal reburning has the lowest NOx emission, while the traditional air feeding has the highest NOx emission. Under the test conditions, the higher the proportion of the reburning coal, the higher the NOx control can reach.