Abstract: Microseism, as a kind of regional monitoring means, is used to predict and forecast the great dynamic force calamity of the mine. Simultaneously, its typical features are that the composition of spectrum is abundant and the frequency band is wide. To obtain the sudden change time of the unusual microseismic signal and the corresponding frequency composition is a key problem demanding to be solved promptly in microseismic monitoring. In order to differentiate microseismic signals from the spectrum, the power spectrum and amplitude-frequency character of two typical kinds of microseismic signals were analyzed with the technology of time-frequency analysis. Thus it would offer a new way for monitoring and predicting the great dynamic force calamity of the mine.