Abstract: We calculated and analyzed about ten years′ data on geomagnetic loading-unloading response ratio value P (Z) from magnetic stations in Zhejiang, Shang hai and Jiang su Provinces, and studied the relation of ten earthquakes which occurred in the three provinces and their vicinity and changes of the P (Z) and its monthly averag evalue P_M(Z). The results show that it is not acomplete linear correlation between the threshold value P₀ (Z) or P_M(Z) and the seismic m ag nitude or the epicentral distance or the o ccurrence time of anomalous P(Z) and P_M (Z). When P(Z) ≥ P₀(Z) at astation an earthquake maybe occur nearby.
On the basis of synthetic analysis by this method, a strong earthquake with M_S ≥ 6.0 may occur in the research region or more largely area(including Taiwan area) within one year, by the end of September 1998. This method can be used as a new routine tool for judgement of the medium-short and short-term and imminent seismic tendency.

Key words: Geomagnetism, Dailyrange, Loading-unloading response ratio, Threshold value