The carbon emission of units can be greatly reduced by the power generation of coal-fired units mixed with hydrogen rich fuel. It is expected to be an important way for coal-fired units to achieve carbon emission reduction in the future. A thermal calculation and analysis of 300 MW power plant were studied based on the energy conservation law. The influence of the unit′s mixed combustion mass ratio of 20%-100% NH3 power generation on the coal-fired unit under different working conditions was analyzed through the boiler thermal check calculation. The results show that after coupling with 20%-100% NH3,the theoretical combustion temperature decreases linearly,the flue gas temperature at he economizer exit reduces slightly,the temperature of exit flue gas rises,the boiler thermal efficiency decreases by 0.31-2.04 percent points,the attempering water consumption increases,and the original heating surface can meet the requirment of heat exchange. Through adding the specific burner,the NOx emssion can achieve the same level as that of the original boiler,and the maximum annual emission reduction is about 1.12 million tons of CO2. The induced draft fan needs to be expanded,which has little impact on the original air supply system,denitrification and desulfurization system. It may be necessary to adjust the low-temperature flue gas waste heat recovery system and investigate the wet electrostatic precipitator or other new system to reduce the aerosol emission.