Abstract:Using the data of Beidou GEO satellites in the Asia-Pacific region, we study the geomagnetic storm phenomenon that occurred in the middle and low latitude regions in May 2017. The accuracy of the global ionospheric map (GIM) is evaluated using the measured TEC data obtained by Beidou GEO satellites, and the global response of the ionospheric TEC of this geomagnetic storm is further analyzed. It is found that the response of the ionospheric TEC to the geomagnetic storm occurs 1 to 4 hours after the start of the main phase of the geomagnetic storm and the maximal disturbance value could reach 20 TECu.