Abstract: In the design of Qinshan Ⅱ nuclear power plant, Fluid-Induced Vibration of the reactor internals has been studied with the combination method of experimental and theoretical analysis. For the theo- retical analysis of core barrel, a special methodology has been adopted. This paper describes the analysis process of this method, deduces the theoretical basis, puts forward the restriction conditions for usage, and studies the applicability in Qinshan Ⅱ. It is considered that this method has definite theoretical foundation and it could be used in the engineering design if the restriction conditions are satisfied. The engineering practice of Qinshan Ⅱ may have some limitation in satisfying the restriction conditions simultaneously, especially for the characteristics of excitation spectrum, damping, and nonlinear effects. Farther theoretical and engineer application study should be devoted in this field.