Abstract: After having studied the relationship of time and space of the seismicity of M_s≥7.0 in the three "earthquake entrance windows" in the adjacent area of Mainland China and of the seismicity of some M_s≥6.0 earthquakes in the inland area, we have discussed how to use this relationship to predict the time and space of M_s≥6.0 earthquakes in Mainland China so as to provide a useful reference for the tendency prediction of large seismic situation. Finally we have discussed the physical meaning of the "earthquake entrance windows".