Abstract: Nowadays structural systems become more complicated with the need of more muti-functions and peculiar aesthetic views. A mega-structure with belt trusses and outrigger trusses is therefore studied. The method of performance-based aseismic design is utilized to evaluate its seismic behavior. The aseismic performance design objectives and corresponding parameters are proposed for the structure under various seismic loadings from frequent earthquake of intensity 7 to rare earthquake of intensity 8. A shaking table model test, the nonlinear time history analysis, tests and stress distribution analyses of important joints have been made. Experimental and analytical studies are verified and complemented each other. Obtained results demonstrate that the structural dynamic performance meets the design requirements.