Large eddy simulation(LES)has become a promising tool for pulverized coal combustion with the development of computational fluid dynamics(CFD)technologies in recent years.LES can better capture the unsteady features and turbulent structures of coal jet flame than Reynolds averaged Navier Stokes(RANS).The coal-fired power plants in China are now required to be operated in a wide load range and quickly respond to the electric grid.The boiler performance of variable loads should be evaluated in terms of flow,heat transfer,and combustion processes.In this paper,LES was applied to simulate a 660 MW ultra-supercritical boiler under BMCR(boiler max-imum continue rate),75％THA-100,and 50％THA-100 conditions.The predicted gas velocities agree well with the thermal calculation and the temperature error is less than 130 K.The simulation results show that the operation load has significant effects on the boiler performance.It is also proved that LES can provide guidance for the design and operation of advanced coal-fired boilers.