Establishing a localized carbon footprint accounting system for products in China is crucial for fostering new productive forces and enhancing the international competitiveness of the country. This study aims to address current challenges faced by carbon footprint accounting, including the absence of standardized systems, weak data foundations, and green trade barriers. It analyzes the intrinsic requirements and methodological framework of carbon footprint accounting in respects of goal setting, accounting processes, and underlying logics. A technical pathway for the localized carbon footprint accounting of products is proposed in three procedures: defining basic unit processes, analyzing material and energy flows, and adopting expandable structured modeling, illustrated with an example of the lithium battery industry. The study indicates that defining unit processes should trace the process and supply chains layer by layer back to bulk basic raw materials. Utilizing meta-analysis to establish input-output inventories for unit processes helps enhance the transparency and completeness of these inventories. Based on basic unit processes, it is recommended to portray three key types of flows: material, energy, and waste emission flows. These flows can interact with national greenhouse gas emission factors and allow for dynamic adjustments to product carbon footprints in response to technological advancements and energy structure optimization. Carbon footprint accounting should employ expandable structured modeling methods, using matrix operations to associate basic unit processes layer by layer along the supply chain. This approach facilitates integration with enterprises' production management systems and aids enterprises in mastering practical application methods. Furthermore, the study offers the following recommendations: (1) leveraging China's industrial system advantages to establish a national high-resolution database for greenhouse gas emission factors and a database for key product carbon footprint factors across dimensions of time, space, technology, and scale; meanwhile, ensuring the integration and mutual recognition with international databases and standards; (2) establishing a data classification and grading system, to thoroughly assess the impact of international outflows of carbon-footprint-related data and ensure the orderly and secure disclosure of the data; (3) exploiting the advantages of China's nationwide system to build a service system aimed at enhancing enterprises' carbon accounting capabilities and improving carbon footprint data management.