Abstract: The prediction method of seismic modulating ratio is proved in this paper. The seismicity dataare used to space scanning in North China byuse of the proven method of seismic modula ting ratio Rm10. The result show sthat in mid-term about 1～3 years before most strong earthquakes there are obviously anomaly zones of Rm10 in the neighborhood of epicenter in general. This method has very good effectsin mid-term earthquake prediciton.

Key words: Seismic modulating ratio, Tidal generation force, Space scanning, Mid and short term earthquake prediction