Abstract: In the past analysis the seismic activity of Xingtai area is considered as a "seismie window" that is used to observe the crustal stress field of North China and predict the moderately strongearthquakes in this district.In this paper, mathematical statistic results are used to analyse and judge the seismic activity anomaly in Xingtai area and it is pointed out that the "seismic window" not only reflects the ehanging stress in North China or at some local sites near Xingtai, but also reflects the accumulating and eoncentratlng-stress in Xingtai "seismic window" itself.This was ignored in the analysis of the "seismic window" previously.It is significant for the prediction of the moderately strong aftershocks in some old seismic areas where great earthquakes occurred and which are regarded as "seismic windows".