Abstract: The development processes of domestic and foreign power grids were summarized.According to the development of power grids and related technologies,the process of power grid development can be divided into 3 stages.Borrowing from the theory of intergenerational inheritance in social science,a concept of three-generation power grid was put forward,and the main characteristics of the three generations of power grids were compared.The first generation power grid was developed from around 1900 to 1950,featured by small generation unit,low voltage power transmission and small grid.The second generation power grid was developed from about 1960 to 2000,featured by lager generation unit,extra/ultra-high voltage power transmission,interconnected grids,and large-scale power production.The development of the third generation power grid was launched at the beginning of the 21st century,and expected to be completed over 2050,featured by intelligence and non-fossil fuel generation holding a significant share.The third generation power grid is characterized as being intelligent and sustainable.The power grid refers to the general grid in this paper,including generation,transmission,distribution and loads.Therefore the third generation of power grid can also be referred as the third generation of power systems.The new situation and new challenges in the development of power grids were analyzed and the power grid technology development in the next 40 years was forecasted.