We build the buffer zones with a 30 km radius from the zero-value-lines of all nents of the abnormal geomagnetic field in lithosphere of north China seismic region, and statst cal analyze all the Ms≥4.0 earthquakes in the buffer zones since 1900. The results indicate that there are close relativities among the epicenter distribution of large earthquakes with Ms≥7.0 and the zero-value-lines of geomagnetic declination, north component, east component and vertical component of the abnormal geomagnetic field, and the epicenter distribution has the highest relation to the geomagnetic declination with proportion 83.3%.