Abstract: On the basis of data observed by the ionospheric observatories and geomagnetic network in China, the ionospheric f_oF₂ (critical frequency of F₂-layer) anomaly phenomena, geomagnetic low-point displacement and diurnal-variation anomalies of geomagnetic field before Kunlunshan M_S8.1 earthquake have been summarized. Anomaly distribution and characteristics of ionospheric f_oF₂ and geomagnetic variation field have been comparatively studied. The result shows that the temporal-spatial characteristics of short-imminent anomalies of ionosphere and geomagnetic field are consistent. The geomagnetic low-point displacement appeared on Oct. 8, 2001, the boundary of sudden change passed through the epicentral area. The obvious anomalies of diurnal-variation of geomagnetic field near epicentral area and ionospheric f_oF₂ at Lasa observation station are found within one month and half before Kunlunshan earthquake.

Key words: Ionosphere f_oF₂ (critical frequency of F₂-layer), Geomagnetic low-point displacement, Diurnal-variation anomalies of geomagnetic field, Kunlunshan M_S8.1 earthquake