Abstract: On January 15, 2022, a violent eruption of the Tonga volcano generated acoustic-gravity waves that propagated around the globe. Using continuous seismic waveform data from 26 broadband stations of the Ningxia Seismic Network, together with barometric and deformation observations, this study systematically investigates the propagation characteristics, time-frequency features, and spatial variations of the low-frequency seismic signals excited by this event. The results show that approximately 9 hours after the eruption, low-frequency seismic signals lasting more than 2 hours were synchronously recorded at multiple stations in the study area, with an apparent propagation velocity of about 312 m/s, consistent with previously reported acoustic-gravity wave speeds. Cross correlation and continuous wavelet coherence analysis show that there is a significant correlation between the low-frequency seismic signal and the same period pressure disturbance in a specific periodic frequency band, indicating that the atmospheric pressure disturbance can be effectively coupled to the surface through the loading mechanism, causing the low-frequency deformation response that can be recorded by seismograph. The time-frequency analysis shows that the low-frequency seismic signal energy increases significantly in the atmospheric disturbance enhancement stage, and then gradually decays, showing a clear stage evolution characteristics. The waveform of the low-frequency seismic signal is characterized by slow amplitude change, regular waveform and significant periodicity, and the recording characteristics of underground and surface stations are consistent. The amplitude variation recorded by different stations and components have certain differences.