In the new situation, mega cities have entered a new round of rapid development, with electricity demand showing characteristics of diversification and high growth rates. However, with the gradual construction of new power systems under the “dual carbon” goals, urban grid structures have become more complex. Meanwhile, the requirements for urban environmental policies and regulations are becoming stricter. The 220 kV power grid faces multiple demands to enhance power supply capacity, improve safe and stable operation levels, and achieve efficient planning implementation. This paper discusses the planning ideas of the 220 kV power grid for mega cities in China, which comprehensively consider the impact of electricity demand trends, power supply layout, topography, and power channel resources. From the aspects of substation capacity and channel planning, network structure construction, and partitioning, a systematic planning idea for the 220 kV power grid in mega cities is formed in this paper. This idea can guide the planning and development of the 220 kV power grid in mega cities of China and also has good expandability.