In order to avoid the DC bias of transformer caused by HVDC project, a method for optimal location of HVDC grounding electrode is proposed. After studying the influence factors of the DC grounding location that should be considered, such as the earth electrical parameters, power planning requirements, structure and parameters of surrounding AC power network and so on, this paper establishes a correlation model between the DC grounding pole position and transformer DC bias risk. Secondly, it makes the sensitivity analysis and on this basis puts forward the HVDC grounding pole location optimization method. Finally, an AC/DC hybrid power grid is used as an example to verify the effect of the proposed method. The optimization method has theoretical reference for avoiding the DC bias risk of AC grid transformer. This work is supported by Science and Technology Project of State Grid Anhui Electric Power Company and Natural Science Foundation of Xinjiang Uygur Autonomous Region (No. 2017D01C417).