Transmission lines intricately distribute in the Pearl River Delta region and other major cities in high density, which on the one hand influence the environmental landscape, on the other hand compress the human living space. Facing the contradiction between power and environment, how to achieve the harmonious development of power grid and environment is one of the key problems to be solved for future power grid. The concept of constructing the integrated energy underground passage is proposed in this paper. Applying the large-capacity transmission cable and pipeline transmission technology, all the transmission lines will be transferred underground to achieve three-dimensional use of land resources, resolve the outstanding contradiction between power and environment. The underground pipe network construction process in developed areas should be comprehensively optimized, considering the energy transmission passages, construction of information delivery passages and rail transport corridors, to achieve the widely shared underground corridors. Current technical development situation of large capacity DC cables, and AC and DC transmission pipelines is also analyzed.