Abstract: An earthquake loss analytical methodology based on collapse margin ratio of RC frame structures was investigated to study the relationship between structure collapse resistance capacity and structural earthquake loss in this paper. Incremental dynamic analysis (IDA) was used to determine structural vulnerability under continuous earthquake intensity. Earthquake losses were estimated according to the structural damage probability using fragility curves, which were combined with the collapse margin ratio (CMR) to produce an earthquake loss model based on CMR. The differences in collapse probability curves and the earthquake loss estimates between ductile and brittle structures are identified systematically. The analytical results from four RC frames show that a close relationship between the seismic loss assessment and CMR of the structure appears to exist. The earthquake loss basically decreases with increasing CMR at a given ground motion intensity; The loss of structural integrity in structures with smaller CMR increases quickly with increasing ground motion intensity, while structural loss in structures with greater CMR increases slowly. The idea proposed herein could be regarded as a promising improvement on the quantification of earthquake loss estimates by utilizing structure CMR.