Brief discussion on design principles of over-limit frame-supported structure. Through analyzing the deign process, we endeavor to illustrate that for relatively complex structure system, due to the lack of clear specifications or normal requirements from current design codes, need to back to the basic deign principles of structural design. Firstly, need to set the fortification level of seismic deign, under the small, medium and great earthquake respectively, for different parts of the structure and under different forces. Then proceeding with purposive structural analysis, base on the different anticipations and acquiring the corresponding and reliable internal force values. This way, the actually structural status can be reflected and finally secure the safety of the structure.