Mixed three wastes fuel fired CFB boiler applies the combustion characteristics of CFB boiler integrated with technical feature of return feed recovering , adpots the pattern of blow-air waste heat boiler, makes the blow-air and slag from fixed-bed gasifier production as well as fine ash from dust collector mix with parts of coal gangue, bitumite or anthracite, get fluidized combustion inside the mixed three wastes fuel fired CFB boiler to produce the hot flue gas, and recover the waste heat. The mixed three wastes fuel fired CFB boiler used ammonium production is not only environmentally friendly, but also produces steam with high energy, bringing maximum social benefits and environment protection for companies.