Abstract: By studying and analyzing the characteristics of seismicity with M_S≥5.0 before twelve great strong earthquakes (M_S≥7.7), the time interval of M_S≥5.0 earthquakes and great strong earthquakes, and the location of the earthquakes with M_S≥5.0 and M_S≥7.7, it indicates that one year before the earthquakes with M≥7.7 and within the range of 600 km², at least one earthquake with M>5.0 occurs. The location of earthquakes with M>5.0 are usually situated on the same or opposite side of the active block, where the earthquakes with M≥7.7 will occur. No matter what seismicity with M_S≥5.0 is active and quiet, this phenomenon occurs everywhere and typical.

Key words: Great strong earthquake, Active block, Earthquake with M≈5.0