In structural dynamic testing and damage detection, the low-order modal information of a structure can be easily obtained, which reflects mostly the global behavior of the structure rather than the local characteristics of the structure. By using the theoretical and experimental modal analysis, this paper investigated the high-order modal properties of the frame structures and the relationship between the high-order modal parameters and the local characteristics of the frame structures in order to implement damage diagnosis of the structures. The theoretical modal analysis showed that there was a dense high-order mode section and the high-order modes behaved the local characteristics in the frame structures. A local exciting method was used to obtain the high-order modes information on a reinforced concrete frame model by the experimental modal analysis method. It was known from the testing results that the stiffness change of a column in the frame structures could be detected by the maximum energy high-order modes.