Abstract: In this study,the natural frequencies of Normal Residual Heat Removal Heat Exchangers are evaluated based on the beam and shell-beam finite element models.The corresponding results are compared and some discrepancies are observed.These discrepancies are analyzed in terms of the analysis of a cylindrical shell and the unreasonable treatment of boundary conditions is accordingly pointed out.The experimental data of the natural frequencies of heat exchangers used for Qishan Phase I Nuclear Power Plant are compared with the computational results from the shell-beam models for corresponding heat exchangers of C-2 program.The experimental and numerical results agree quite well,which implies that the shell-beam finite element simplification is applicable to the heat exchangers.The results indicate that the procedures introduced in this article apply to the dynamic analysis of other similar heat exchangers.