The ground vibrations are consistently measured by broadband seismometers to explore the physical correlation between the change of ground vibration with earthquake precursor. The continuous waveform data was selected from 15 broadband seismometers within 500km of the epicenter before and after the M_S6.0 earthquake in Changning,Sichuan Province on June 17,2019. The amplitude spectrum of low frequency signal(8×10^-5～2×10^-4Hz) of ground vibration was analyzed by Fourier transform,and the source of the signal is located to study the evolution law and physical characteristics of anomalies before and after earthquake. The results show that the low frequency signal recorded at the several seismic stations in this area is enhanced 10 days before Changning earthquake. The source occurred within the range of 100km in the focal area near 2 days before EQ. The time scale and space area are about same as that of Changning earthquake. We conclude that the analysis of ground vibration using continuous waveform data is essential for the short-term and imminent prediction of earthquake.