Some parameters related to energy of seismic waves E are applied extensively to earth-quake prediction as criteria of seismicity.In general,temporal variation of total areas of seismic.faults ΣS is used for earthquake prediction.In this paper,well use the parameter ΣE^2/3 relat-ed to Σ S to plot the curve of ΣE^2/3-t and analyse its temporal variation before a large earth-quake.Analysing the curves of ΣE^2/3-t before M_S ≥ 7.0 earthquakes since 1900,we obtain that the seismicities in past years in a region are known by the E^2/3(t) curve of historical earth-quakes in the area,and from this the whole state of seismicity in the region from a few years to a few decades in future is estimated;the possible magnitude of recent seismicity in the regionmay be extrapolated and assessed from the curves.Also the basic shapes of E^2/3(t) curves are classified roughly.In this paper,the catastrophe condition and time of the E^2/3(t) curve of historical earthquake series in a region are determined from view of catastrophe theory,and the mathematical and physical methods for earthquake prediction are found.