By studying the evolution process of seismic gaps before M≥7.0 earthquakes occurred in the western part of China mainland from 1970 to 2010,it was suggested that the spatial distribution evolution process of moderate and strong earthquakes showed relatively regular before M≥7.0 earthquakes,which showed that M≥6,M≥5and ML ≥4 earthquakes gradually appeared very quiet in a large area at the same tectonic region,forming seismic gaps with different magnitude intervals.The evolution process of such patterns is the guidance of the pregnancy zone of M≥7.0 earthquakes,and has an important effect on the medium-term prediction on the M≥7.0earthquakes.