With the development of earthquake engineering in China, the application scope of intensity has gradually changed. From the collected seismic damage data over more than half a century, it is found that in low-intensity regions, the proportion of similar building structures in basically intact state increased, and the proportions of other damage states decreased; while in high-intensity regions, the proportion of similar building structures in complete damage state increased. From the seismic damage data of Wenchuan earthquake, Lushan earthquake, and Ludian earthquake in recent years, it is found that in the same intensity area, the damages of fortified structures, unfortified structures, and structures with different fortification intensities are quite different. If the intensity represents the earthquake consequences, the intensity evaluated by the average level of earthquake damages should be different, thus implying that the meaning of intensity is the seismic action reflected by earthquake damage. Therefore, when we determine the intensity according to different types and different fortification levels of structures, a relatively unified standard is needed. Since the abundant damage data in China are from unfortified structures, it is suggested to establish the adjustment coefficients of average damage index/damage ratio corresponding to unfortified structures based on the statistical relationship between the average seismic damage index and (or) damage ratio of different fortification standards, various structures, and seismic damage levels of structures under a certain intensity and the average seismic damage index and (or) damage ratio of similar structures without fortification. The intensity could be determined by the damages of fortified structures.