The invention relates to an emission reduction system of sintered fume nitric oxide with low energy consumption and a method thereof. The system comprises a nitric oxide high-concentration region air bellow A, a nitric oxide low-concentration region air bellow B, a denitration dust remover, a denitration device, a dust remover, a desulfuration device, a main exhaust fan, an emission chimney and a circulation loop. The denitration dust remover is connected with the air bellow A to collect the fume in the air bellow; the denitration dust remover is sequentially connected with the denitration device and the desulfuration device; and the fume subjected to dust removal and denitration is guided into the desulfuration device. The dust remover is connected with the nitric oxide low-concentration region air bellow B to collect the fume; the dust remover is connected with the desulfuration device; and the fume subjected to dust removal is guided into the desulfuration device. The desulfuration device is sequentially connected with the main exhaust fan and the emission chimney so as to desulfur the fume and discharge into the atmosphere. The circulation loop at least comprises a circulation fume hood, a circulation blower, a circulation fume dust remover and a circulation pipeline. The method comprises the following steps of collecting fume, removing dust, denitrating, desulfuring, discharging fume into the atmosphere and the like. The whole system is relatively simple and has obvious effects of energy saving and emission reduction.