Based on the research of Life Ring in Shen Fu, the basic criteria for structural design of the unconventional rigid mega-structure linked with the ground are proposed in this paper. Through the structure comparison and selection, the space steel truss is used as the optimal structure form. After static analysis and time-history analysis by FEM, it is found that the control load case is the combination of dead weight and wind load. Because of its long vibration period, the structure is not sensitive during an earthquake. The key design of the structure is the selection of foundation form, a mixed-foundation made of steel trusses with piles is proposed in this paper. The steel truss is used as a bridge which transmits forces between superstructure and foundation. At last, the pile foundation is classified by the loading mechanism, the analysis and design of key joints in the mixed-foundation is proposed.