///Spatio-temporal variation of seismic activity before the great Chile earthquake is studied. Some results are as follows: 1) two types of seismic gaps appeared before the Chile MW8.8 shock; 2) this is the long-term background anomaly of the obvious quiescence of MW≥7.0 earthquakes before the Chile earthquake; 3) the quiescence of earthquakes with MW≥6.5 appeared in South American Plate and its vicinity during 2007~2009, and the quietude state has been disappeared three months before the MW8.8 shock; 4) the deep and intermediate-depth earthquake activity has been noticeably strengthened in the subduction zone of South American Plate since 1993; and 5) the great Chile earthquake shows that the global seismicity is still in the active period of MW≥8.5 earthquakes since 2004. Based on the characteristics of the former two active periods, several MW≥8.5 great earthquakes would take place in a few years.