Major manufacturers worldwide are beginning to take the green management of supply chains more seriously. ASE hopes to gradually promote carbon management measures to suppliers by assisting suppliers with the implementation of ISO 14064-1 Greenhouse Gas (GHG) management systems. This will allow suppliers to monitor their energy use and carbon emissions, and further lower their operating cost and improve their business reputation. In 2018, ASE and National Cheng Kung University (NCKU) Industrial Sustainable Development Center (ISDC) jointly carried out the guidance project for the implementation of ISO 14064-1 GHG Inventory by 10 suppliers, in hopes of further developing a green supply chain.This study adopts the SROI methodology to review project data from May 3, 2018 to April 12, 2019 from the perspective of stakeholders. After engaging stakeholders, we found that the project’s main impact is improving the business reputation of suppliers that received guidance, and strengthening the energy conservation and carbon reduction concepts of the organization and employees. This changes the company’s procurement decisions and individual purchase choices in daily life to further increase environmental benefits.