Abstract: The mega column design is one of the key points in the structural design of CITIC Tower. The integrated design method of building structure is adopted to control the geometry of the mega-column to realize the unity of architectural effect and structural force transmission. Through appropriate cavity structure design, it can solve the complicated cross-section changes of the mega column, while ensuring its reliable force transmission and convenient construction. The slab stiffness has a significant influence on the effective length of the mega column. By analyzing the variation of the effective length, the economical value of the effective length was determined. Through the finite element analysis, the safety of the key joints such as the mega column branching joint, the mega column and the transfer truss joint was verified. In this project, non-embedded column foot was adopted, and wing wall was set to diffusion the column force. The column foot reliability under non-yielding in rare seismic was verified by finite element.