Abstract: This paper is a summary about stress analysis and evaluation of the internal structures for China Experimental Fas Reactor. The summary includes stress analyses and evaluations of internal support structure, core support structure, reactor thermal shield, etc. Analysis of the internal structures using finite element method was performed. At first， structural calculation models were built. Then, static analysis and dynamic analysis were performed under dead weight load, pressure load, the load induced by fluid flow, thermal load and seismic load. Finally, load combination and evaluation were performed.