Abstract: Seismicity pattern characteristics before and after the Bohai M7.4 earthquake of 1969 are analyzed,including time-space distribution of large earthquake series,precursory seismicity patterns characteristics,equidistant migration of large earthquakes,chief interval shortening,conjugate faults' creep slip,microearthquakes zonation,phenomena of induced foreshock.The anomaly of earthquake triggering coefficient is extremely obvious.Since we pointed out the character of earthquakes' interaction and self-organization,it makes long term earthquake prediction possible.