Abstract: In the design of intermediate heat exchanger (IHX) for demonstration fast reactor plant, the influence of flow induced vibration should be considered. The structure of the space elbow tube is a technical difficulty for inherent frequency calculation of IHX heat exchange tube. Inherent frequency of China Experimental Fast Reactor (CEFR) IHX heat exchange tube was calculated by using finite element method. Through the comparison and analysis, the reasonable calculation model and its applicable range are obtained. The design principle of tubes support is propounded by sensitive analysis.