Based on a study of non-seismometric precursory anomalies, such as short-levelling, earth electricity, water radon content and water level, during four earthquakes, it is found that anomalous values of these precursors occurred before the earthquakes in the Xintai region, indicating that there is not only a window effect of seismic activity, but also the window effect of seismic situation in the region. A similar phenomenon is also found in other regions.