Abstract: Based on China seismic network catalog, after the integrity assessment of the catalog and to determine the threshold magnitude, the fluctuation characteristics of seismic activity in Inner Mongolia Wulatehouqi-Linhe area and the relation between seismicity and strong earthquakes in the northwestern margin of Ordos block were analyzed. The analysis shows that there is a good correspondence between the increase of earthquake frequency and the moderate strong earthquakes in the northwestern margin of Ordos block. The half year frequency of M_L ≥ 2.0 earthquakes greater than or equal to 13 can be used as a predictive index of M_S ≥ 5.0 earthquakes. The prediction time is one year after the appearance of the anomaly. The R value score test and Molchan chart test showed that the forecast performance of earthquake frequency is significant.