Abstract: Basing on the anomalous patterns of seismic activity, this paper quantilatively describes anomalous variations in regional earthquake migration "rate" prior to 5 great earthquakes.The result shows that the low value of lgs/lgT prior to the 5 great earthquakes is obvious.The variation in lgs/lgT is basically synchronous with the variation in seismic actvity and anomalous patterns of seismic activity.The variation in rate parameter is directly related to seismic activivties before great earthquakes.It is roughly considered that the rate parameter reflects the comprehensive characteristics of seismic quiescence and dense seismic activity.