Abstract：Seven underground explosion experiments that explosion equivalent is 100 kg TNT are carried out in the loess，and the ground motion signals are measured by four acceleration sensors laid in the range of 1 000 m away from the explosion source. By applying Wigner-Ville distribution to analysis the measured signals，the time-frequency characteristic parameters of the signals and its energy distribution are gained. The analysis shows that the ground motion signal in the loess is mainly composed of two center frequencies，respectively，in 4–10 and 11–16 Hz. The signal energy lies within 30 Hz，and the dominant frequency is in 8–15 Hz. According to the results，there are the obvious relations between the characteristic parameters¢ value of Wigner-Ville distribution of the ground motion signal and the distance away from the explosion source. Based on the analysis of the signals，as the distance away from the explosion source，it is found that the energy of the Wigner-Ville distribution¢s peak attenuates exponentially，the frequency corresponding to the Wigner-Ville distribution¢s peak reduces logarithmically，and the time corresponding to the Wigner-Ville distribution¢s peak increases linearly.
