Abstract: A new simplified analytical model was developed for structural analysis of the space frame of super tall buildings, in which the axial rigidity of subsidiary columns within the space frame is idealized continuously as Winkler elastic subgrade along the axes of the mega beams. The interactions between the subgrade - foundation and the superstructure were analyzed. Afterwards a more reasonable model was presented, in which the mega columns were also simplified as members with shear-typed elastic subgrade obtained by bending rigidity of the subsidiary frames within the mega frames. Based on these models and considering the foundation and the subgrade, this paper presents an improved analytical model for the interactions between the subgrade and the foundation and the superstructure composed of the Winkler-elastic-subgrade beams and the shear-typed elastic-subgrade columns. It is observed through computing example that the improved interaction-model is reasonable. A practicable simplified method for the global static analysis of the super tall buildings with space frames is thus investigated. Some significant conclusions are as well presented so as to propose a suggestion to conceptual design of super tall buildings with space frames.