Abstract: With the deepening of national energy conservation and emission reduction efforts and the increasingly stringent environmental protection regulations, the incineration of household waste for power generation has gradually adopted the ultra-low emission requirements, and NO_x concentration control has become a problem that must be addressed. To investigate the flue gas denitrification process in waste incineration power plants, a combined denitrification system model for waste incineration power generation was established and its validity was verified. Different moisture content levels of municipal solid waste （MSW） were selected as fuels to study the effects of ammonia-to-nitrogen ratio and excess air coefficient on the combustion characteristics of the waste incinerator, ammonia injection rate, denitrification efficiency, and ammonia slip in the combined denitrification system. The results show that, when the excess air coefficient is 1.7, the optimal ammonia-to-nitrogen ratios for the SNCR and SCR systems under MSW1, MSW2, and MSW3 fuel conditions are 1.6, 1.5, 1.2 and 0.94, 0.86, 0.78, respectively. As the moisture content of the waste increases, the water content of the flue gas in the furnace increases, the SNCR reaction temperature decreases, and the SNCR denitrification efficiency increases, while the SCR reaction temperature and denitrification efficiency decrease. As the excess air coefficient increases, the furnace temperature decreases, the mass concentration of NO_x in the flue gas at the top of the furnace is reduced, the amount of ammonia injected by the SNCR decreases, the reaction temperature and the amount of ammonia injected by the SCR are lowered.