Abstract: The Boketu earthquake of February 10, 1980 of magnitude 5.6 occurred at the northwestern boundary of the Song-Liao basin is the largest earthquake in the northeast Part of our country in the past thirty years. In the paper, the characteristics of seismic activity of moderate small earthquakes before this earthquake was systematically studied in six aspects, the useful seismic precursory information has been offered for monitoring the occurrence of moderatetorng earthquake in the northeastern part of China where less earthquakes occur.