Abstract: The first structural material irradiation rig used in China Experimental Fast Reactor (CEFR) was designed in order to carry out irradiation test for domestically produced fast reactor cladding material. The innovated design of irradiation rig was based on both the CEFR irradiation conditions and the basic configuration of CEFR fuel assembly. The irradiation rig which had special sizes of inner gas gaps could irradiate material samples at different irradiation temperatures (450-600 ℃) during different powers (40% and 100% rated powers) of CEFR steady state operation. There are indicating samples inside the irradiation capsule for monitoring temperature range and neutron fluence rate. The irradiation rig has a general configuration which can realize the maximum loading for the standard irradiation samples and be used as a standard irradiation device for reactor structural material irradiation in CEFR. The design of irradiation rig can satisfy the requirement of material irradiation by means of thermal-hydraulic analysis and relevant out-of-pile heat transfer, flow resistance and structure stability verification tests.