The vigorous development of new energy has made fundamental changes in the mode of supply and usage of traditional energy. Meanwhile

the new situation in the coexistence of power generation of large coal power

hydropower

photovoltaic and wind energy has brought great challenges and profound innovations to the traditional power transmission technology. The DC power grid based on traditional line commutated converter(LCC)and flexible voltage source converter(VSC)technology is investigated

and the research trends of DC power grid planning are reviewed. Firstly

the features and advantages of DC power grid are analyzed

and the framework of DC power grid planning is put forward and elaborated in detail. Then

the research ideas based on two application scenarios for DC grid planning are proposed

including the access of new energy to grid

multi-infeed and multi-terminal DC network. The multi-power electronic equipment co-optimization DC planning is also discussed. Finally

the preliminary planning of the demonstration project of the Zhangbei ±500 kV flexible DC power grid is briefly analyzed. And the key issues and prospects for researches of DC power grid planning in the future are provided.