This paper studies the influence of DC bias on transformer and substation grounding grid around the grounding pole of ±1100 kV Guquan converter station.The DC bias current distribution of transformer in the surrounding AC power grid is analyzed,and the corresponding DC resistance network coupling model is established.At the same time,on the basis of the above research,combined with the withstand current limit of transformer DC bias,the corresponding DC bias control range and DC bias control scheme are proposed,and the reference for the location of grounding electrode in east China is provided.