As　an　important　link　and　bridge　for　emission　reduction,　power　grid　companies　are　more　willing　to　build　clean　power　transmission　and　transformation　projects　under　the　＇3060＇　carbon　emission　target.　With　this　problem　at　its　core,　this　paper　uses　a　typical　220　kV　line　and　substation　in　a　province　as　the　case　data.　This　study　improves　the　carbon　emission　measurement　method　for　the　entire　lifecycle　of　power　transmission　and　transformation　equipment,　compiles　and　summarizes　the　carbon　emission　coefficients　of　each　equipment　and　duration　according　to　different　typical　scenarios,　and　measures　the　carbon　emission　of　power　transmission　and　transformation　projects.　The　results　show　that　the　carbon　emission　of　the　line　is　8169.58　tons,　mainly　concentrated　in　materials　such　as　steel,　water,　concrete,　and　cement;　the　carbon　emission　of　the　substation　is　4483.48　tons,　mainly　concentrated　in　materials　such　as　concrete,　cement　and　steel;　and　the　carbon　emission　of　the　operation　and　maintenance　stage　is　9939.70　tons.　The　carbon　emission　coefficient　in　this　paper　can　be　extended　to　all　the　carbon　emission　accounting　of　power　transmission　and　transformation　projects　in　China.　©　2025　by　the　authors.