Regional seismicity characters before and after the Main MS 7.5 earthquake on Nov.8, 1997 and its far-field precursors are analyzed and studied.The results show that before the earthquake, a gap of M_S ≥ 5.0 earthquakes has been formed in the south of the epicenter and frequency of M_L ≥ 4.0 earthquake along Zangbei seismic zone decreased;Ground stress of Delingha station which is to the east of the epicenter and 940 km distant from it and groundwater temperature of Geermu station which is about 600 km distant from the epicenter have shows of short and impending anomalies.The background of the earthquake and stress field adjustment after the event are approached.