Abstract: Carbon footprint accounting for steel products relies on Life Cycle Assessment （LCA）. In practice, LCA applications in the steel industry have diverged into two functionally distinct forms. Analysis-LCA is anchored in physical material flows and serves compliance verification and process evaluation, whereas Message-LCA targets the transfer of carbon assets and low-carbon signalling, with considerable accounting flexibility. The concurrent use of these two forms has led to inconsistent accounting practices and undermined the credibility of low-carbon claims, a problem that has not received sufficient attention in existing literature.This paper focused on the operational mechanisms and potential risks of Message-LCA, with Analysis-LCA serving as a benchmark throughout the discussion as its well-established institutional framework and accounting principles provided a reference point for identifying the deviations inherent in Message-LCA. World Steel Association's mass balance approach and the Rocky Mountain Institute's Book & Claim system as the primary objects of analysis, the paper examined how these two tools amplified risks in the absence of adequate regulation. The former reallocated emission reduction attributes among different products through internal credit transfers, while the latter achieved a complete decoupling of emission reduction credits from physical steel products via certificate transactions. The findings indicate that these tools can incentivise process improvements through carbon premiums when properly regulated, but in the absence of institutional constraints, they tend to become vehicles for greenwashing and may discourage genuine low-carbon investment. Based on a comparative analysis of domestic and international regulatory frameworks and typical case studies, this paper proposes several optimisation pathways, i.e. drawing clear application boundaries between Analysis-LCA and Message-LCA, strengthening disclosure requirements for Message-LCA calculations, establishing a triple-ledger management system for steel enterprises, and setting a transition period with a gradual phase-out of virtual accounting tools. The core argument is that the conflict between the two LCA forms does not lie in technical details, but in their fundamentally different functional orientations. The solution is not to deny the market value of Message-LCA, but to design institutional rules that keep it operating within its proper boundaries.