Abstract: Carbon emission accounting in the construction stage of substations has become an important basis for green construction of power transmission and transformation projects and carbon management by power grid enterprises. Taking S Substation as an empirical case, this study accounts for construction-stage carbon emissions based on life cycle assessment. The results show that material and equipment production is the dominant emission source. Further analysis indicates a mappable relationship between carbon-related activities and engineering financial data. The uncertainty of total construction-stage emissions is ±6.83%. These findings can serve as a reference for carbon emission accounting during the construction phase of similar substations and for project carbon accounting.