The pressing challenge of climate change, driven by escalating carbon emissions, necessitates urgent global action and innovative policy frameworks. Among various strategies, Emissions Trading Systems (ETSs) have emerged as a pivotal tool to mitigate greenhouse gas emissions while fostering economic efficiency. However, as countries strive to meet ambitious carbon neutrality targets, China faces a critical specific challenge: the integration and expansion of its nascent national carbon market (CN-ETS) amid the complexities of transitioning from the local carbon market (CL-ETS). And it was exacerbated by data inconsistencies and regulatory complexity. Despite the growing body of research on carbon markets, a significant knowledge gap persists regarding insufficient understanding of how multi-level carbon markets (local/national) can synergistically coexist to accelerate sectoral coverage while leveraging international policy pressures (e.g., Carbon Border Adjustment Mechanism (CBAM)). Our study employs Triangulated Institutional Analysis (policy archaeology, cognitive mapping, quantitative validation) of 346 documents and 22 expert interviews. Key findings reveal: (1) CN-ETS expansion is constrained by Measurement, Reporting, Verification (MRV) bottlenecks; (2) EU CBAM imposes a 2034 deadline for full CN-ETS maturity; (3) CL-ETS pilots retain vital “triple innovation functions” (small and medium enterprise (SME) coverage, carbon finance, regulatory experimentation) under a dual-track coexistence model. We challenge three prevailing assumptions: “domestic priority” (CBAM drives domestic reform), “system-first” (local pilots enable national legislation), and “technological determinism” (political mutual recognition trumps pure tech upgrades). Our framework offers emerging economies a strategic blueprint for carbon market integration under cross-border carbon pressures.