After　the　Chinese　government　announced　its　goals　of　carbon　peaking　and　carbon　neutrality　in　September　2020,　a　series　of　carbon　reduction　policies　have　been　introduced　on　the　energy　consumption　and　production　side　without　taking　into　account　energy　transmission　and　distribution.　To　address　this　issue,　this　paper　introduces　a　new　approach　to　estimate　carbon　emissions　by　extending　the　life　cycle　approach.　It　then　calculates　the　comprehensive　life　cycle　costs,　including　economic　and　carbon　costs.　This　approach　not　only　serves　as　a　basis　for　power　companies　to　consider　when　planning　transmission　and　transformation　projects,　but　also　provides　a　theoretical　basis　for　the　government　to　formulate　carbon　reduction　policies　in　energy　transmission　and　distribution.　Taking　one　220kV　substation　in　Fujian　Province　as　an　example,　the　results　reveal　that　the　life　cycle　economic　costs　are　102.88644　million　yuan,　accounting　for　97.30%,　while　the　carbon　costs　are　2.85628　million　yuan　(the　carbon　trading　price　is　taken　as　the　average　carbon　trading　price　of　60.45　yuan/ton　published　by　Shanghai　Environment　and　Energy　Exchange　on　22　August　2022),　accounting　for　2.70%,　and　the　comprehensive　life　cycle　economic　costs　are　105.74272　million　yuan.&　COPY;　2023　The　Author(s).　Published　by　Elsevier　Ltd.　This　is　an　open　access　article　under　the　CC　BY-NC-ND　license　(http://creativecommons.org/licenses/by-nc-nd/4.0/).