Abstract: On Nov. 18^th,1993 and Apr.17_th,1998,the earthquakes with Magnitudes 4.4 and 5.0 occurred respectively in Baodi County of Tianjin region and Qianying of Tangshan region.Before the first medium size event,the spacial anomaly of seismictity distribution was showed,and before the Socand,the short-impending anomalous change of hydrogeochemistry was showed.In this paper,based on the introduction about above the anomalies objectively,the analysis was made for the cause of the defferent patterns of the anomaly combining with the seismic types and the tectonic background of earthquake occurrence and comparing with the correlation earthquakes.The preliminary knowlege has been obtained about the background conditions and the correlation factors causing the different anomalies.