Taking a 200 MW tangentially coal-fired boiler as an investigated object,numerical simulation methods were used to study the boiler maximum continous rating (BMCR) condition and NO_x emissions in different pulverized coal shades,and the furnace flow field,temperature field and the characteristics of NO_x emissions were thus acquired.It turns out that under BMCR condition,the numerical calculating results can meet the design values in a better way.The main cause of the higher concentration of NO_x emissions is that the chamber excess air coefficient is large and the dual-channel burner's high NO_x emission characteristic is obvious.The best shade of pulverized coal in the actual operation is 5:1.The calculation results can be used as an operation reference for similar boiler.