The invention provides a double coupling system for enhancing sewage in an irrigation district. The double coupling system is characterized by comprising a storage pond, a zero-valent iron/anaerobe coupling system and a constructed wetland/microbial fuel cell coupling system. The sewage enters the zero-valent iron/anaerobe coupling system for biochemical treatment after being simply filtered and homogenized, the treated sewage enters a constructed wetland system in a flow rising mode, the constructed wetland system is coupled with a microbial fuel cell system while deep purification is carried out, an external circuit collects generated electrons, excitation is carried out to obtain an electric field to be used for enhancing the zero-valent iron/anaerobe coupling system, therefore, the biochemical effect is improved, and the treatment efficiency is improved. The double coupling system has the advantages that the whole coupling system supplements each other and enhances each other, and the effluent quality is guaranteed; ground land resources do not need to be occupied, and maintenance and management are easy; no additional energy consumption is generated, and cost is low; running management is convenient, the sewage treatment efficiency is high, and the effluent quality is stable.