During the operation of pulverized-coal fired boiler, essential combustion adjustments are required for the boiler to maintain good operation performance and low concentration of NO_x emission when coal quality and other factors change. Operation personnel can evaluate the impacts of the variations of the factors and the corresponding adjustment measures based on the unit performance and their operational experience so as to determine the better mode and extent of the adjustment needed. The commonly used methods for the prediction and control of boiler NO_x emissions during power plant operation mainly include the empirical method based on combustion tuning tests, the mathematical model method based on optimization control and the method based on CFD simulation and performance analysis. Based on the review on the current status of the investigation and application of boiler NO_x emission prediction and control, CFD technology was applied for the numerical investigation and performance analysis of the boiler with advanced combustion system to realize the goal of safe, stable, highly efficient and low-NO_x operation of the boiler.