Abstract: Assuming that while a strong earthquake is being prepared, the seismic activity will demonstratea process of uniform to relatively uniform to uneven increase,corresponding to the local stress field change, Based on this physical basis, we constitute samples space by using the parameters related to the occurring time of earthquakes to seek the variation coefficient about the earthquake events cluster character on the time axis. By the practical application in recent years, it turned out that the study in occurring time forecast of earthquakes is significant.

Key words: Seismic activity, Physical character, Time variation coefficient, The earthquake occurring time forecast