Abstract: In the paper a new semi-analytical method for three-dimensional free vibration analysis of interactions between semi-infinite elastic subgrade and foundation and superstructure of tall buildings is developed. The various subgrade stiffness parameters for evaluating elastic strain energy stored in subgrade are inferred by using the principle of energy equivalency, This method is applied to analyze the tube-in-tube reinforced concrete structure adopted by Guangdong Guoji Building. The numerical results obtained are compared with that of model test.