The invention relates to a firing system gradient combustion self-denitration technological method, and belongs to the technical field of cement industry flue gas denitration. According to the firingsystem gradient combustion self-denitration technological method, a gradient combustion environment with an extreme oxygen deficient area-oxygen deficient combustion area-oxygen enrichment burnout area is formed in a decomposing furnace; the gradient combustion environment is realized through classified feeding of decomposing furnace inlet fuel, tertiary air and decomposing furnace inlet materials; a furnace inlet tertiary air hose is divided into an upper branched pipe and a lower branched pipe, the tertiary air lower branched pipe is fed in from the lower portion of a decomposing furnace cylinder, and the upper branched pipe is fed in from the middle of the decomposing furnace cylinder; the decomposing furnace inlet fuel is divided into two layers and is further fed into the furnace, thelower layer of the fuel is fed in from a decomposing furnace cone, and the upper layer of the fuel is fed in from the decomposing furnace cylinder; the extreme oxygen deficient area refers to the decomposing furnace area located below the tertiary air lower branched pipe; the oxygen deficient combustion area refers to the area located between the tertiary air upper branched pipe and the tertiaryair lower branched pipe; and the oxygen enrichment burnout area refers to the decomposing furnace area located above the tertiary air upper branched pipe. The firing system gradient combustion self-denitration technological method has the advantages that the process is optimized, reliability is good and the flow path is reasonable.