The invention provides a process for realizing low-cost denitration by utilizing waste heat of sintered ores to heat waste gas. According to the process, flue gas with relatively high NOx concentration in flue gas of a sintering machine is used as a cooling medium to be input into a cooling system for cooling the sintered ores, the part of the flue gas of the sintering machine can be heated to 260-480 DEG C after passing through the cooling system, then the part of the flue gas is input into a denitration system for denitration treatment, then waste heat utilization, dust removal and desulfurization treatment are carried out, and then the emission requirement is met; flue gas with relatively low NOx concentration in the flue gas of the sintering machine undergoes the desulfurization treatment after undergoing the waste heat utilization and the dust removal, and the emission requirement can be met directly, so that the flue gas treatment amount of the denitration system is reduced; andtherefore, the waste heat of the sintered ores in the cooling system is effectively utilized in the process, then the sintering flue gas can reach the required temperature in the denitration system, energy conservation and emission reduction are achieved, and meanwhile, the operation cost of sintering flue gas treatment is reduced.