Abstract: This paper establishes a semi-analytical three-dimensional model for the super tall bundled-tube structure considering interactions between the subgrade, foundation and the superstructure. It is a combination of stiffened-thin-walled tubes with continuously distributed mass and stiffness, and supported on the semi-infinite elastic subgrade. The free vibration analysis of the model is, by principle of energy, transformed into solving eigenvalues of a set of ordinary differential equations (ODEs). The eigenvalues are solved by COLSYS, an ODEs solver. The efficiency and accuracy of the simplified semi-analytical model are verified by an example, and some conclusions are obtained.