In urban centers, there are numerous old masonry buildings that possess poor seismic performance and may suffer damage under the effects of blasting. To investigate the dynamic characteristics of these structures when subjected to blasting, a strong motion instrument was installed near a blasting site on an old masonry building. This allowed for observation of both instantaneous and cumulative damage effects on the structure. By analyzing records of blasting acceleration and velocity in both time and frequency domains, it is concluded that the dynamic characteristics of the masonry structure can be better identified using blasting velocity rather than acceleration. Additionally, it is found that the transverse resonance of the masonry structure is most influenced by the blasting seismic velocity. Furthermore, both blasting seismic velocity and acceleration can approximately identify low order translational and torsional frequencies of the masonry structure. However, when calculating natural vibration frequency, it is observed that using blasting velocity yields a lower value (1.8%~3.4% lower) compared to calculations based on ground pulsation methods. This discrepancy arises because blast vibrations provide a more accurate reflection of structural response under larger vibrations. Moreover, frequent blasts may induce nonlinear responses in old masonry structures. By monitoring changes in natural vibration frequency over time due to long-term exposure to blasts, it is determined that with increasing blast frequency, first-order torsional frequency decreases by 4%, second-order transverse frequency decreases by 3.6%, and second-order longitudinal frequency decreases by 5.2%. These reductions occur even though individual blasts meet safety regulations, thus highlighting the importance of considering cumulative damage effects from long-term exposure to blasts for old masonry structures with poor seismic capacity during safety monitoring.