The utility model discloses a self-supporting catalytic reduction flue gas denitration reactor. The prior reactor carries very big load, so the increased stress of a reactor member can be caused by uneven release, and the reactor can be destroyed when the stress value exceeds the permissible value of materials. The denitration reactor comprises a shell, supporting posts arranged on the shell, a supporting truss arranged in the shell, and catalysts. The denitration reactor is characterized in that the center of the bottom part of every side of the reactor is provided with a guiding device, and limit devices are arranged at the bottoms of the supporting posts. The utility model can reduce the stress caused by expansion to an ignored degree to meet the requirements of mechanical properties, and ensures the safe operation of the reactor.