Abstract: A new concept of “sub-moderate earthquake” is proposed, and then a multi-level force controlled pushover method is put forward, which builds up the corresponding relationships between four levels of seismic fortification (namely, minor, sub-moderate, moderate and major earthquakes) and four levels of global limit states of structures(namely, minor damage, moderate damage, severe damage and collapse). To consider the randomness in structures, a multi-level force controlled random pushover method is put forward, which combines Monte Carlo Simulation method with multi-level force controlled pushover approach. The proposed method is applied to a R.C. frame structure, for which the fragility curves of the global seismic capacity of the structure are obtained.