Abstract: The spatial mega-frame structure and its foundation of a super tall building are simplified equivalently and continuously into a three-dimensional model,which is a combination of stiffened thin-walled tubes on semi-infinite elastic subgrade.The interactions between semi-infinite elastic subgrade and spatial mega-frame structure of a super tall building space-mega-frame structure under static loads are computed and analyzed with the three-dimensional model by semi-analytical method based on ODE(Ordinary Differential Equation) solver.A numerical example is given to verify the effectiveness of the model.Some valuable conclusions are drawn from the results of the numerical example.