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The geomagnetically induced currents (GIC) caused by geomagnetic storms can inflict the anomalous operation of power systems, damaging electrical equipment, or even resulting in a large-area blackout of power systems. Therefore, to reduce the impact of GIC and avoid severe disasters has been a major challenge for the development of large-scale power grids. Considering the fact that geoelectric field may have random orientation in mid-low-latitude areas, this paper employs GIC-Benchmark model, to calculate the GIC of East-China 1000kV ultra-high voltage (UHV) and 500kV extra-high voltage (EHV) power grids under a uniform geoelectric-field of 1V/km. We further analyze the characteristics and the pattern of GIC in UHV power grid and identify high-risk nodes which can be vulnerable to GIC encroachment. Then we propose installing additional resistors in the transformer neutral points of high-risk nodes to even the GIC distribution in whole networks, and make the theoretical calculation of GIC in East-China 1000kV power grid after installation. The results show that the principle of GIC-even distribution can reduce edge effect remarkably, which works well in mid-to-low- latitude areas at least, thus we expect to avoid space weather disaster in power grids with power operation scheduling and other mitigation methods.