The power supply contributes a major source of greenhouse gas (GHG) emissions. Besides the electricity generation process, the electrical facility also contributes to significant direct and indirect carbon emissions. However, there is still a lack of measures to assess the level of carbon emissions from the facilities. In this paper, the model used for carbon footprint assessment by life cycle assessment (LCA)  towards power transformer was set. The model structure was optimized for ease of application according to the actual manufacturing process and site monitoring level of GHG emissions. After that, the carbon footprint of a 220kV power transformer is studied according to the proposed method, and a quantitative evaluation of carbon footprint in the whole life cycle of the facility was conducted. Based on the carbon footprint calculating results on the manufacturing process, transportation process, running process, and end of life process of power transformer, it is revealed that the carbon footprint in running process takes up a large part. in terms of the manufacturing process, the carbon footprint aroused by raw material accounts for more than 90 percent. This study indicates that the decarbonization of raw materials and the improvement of operating efficiency could be major concerns in optimization design on the carbon footprint of power equipments. 

life cycle assessment,carbon footprint,,power transformer,optimization design