Abstract: Under the backdrop of “carbon neutrality”, the synergistic conversion of methane and carbon dioxide is considered one of the key pathways to achieve greenhouse gas emissions reduction and high-value utilization of carbon resources. However, the current methane dry reforming process suffers from high energy consumption, severe side reactions, and difficulty in product control; while the electrocatalytic CO₂ reduction process faces issues such as poor temperature matching, high electrical energy consumption, and low reaction efficiency. How to achieve efficient synergy among heat sources, power sources, and carbon sources, and establish an integrated energy conversion system, has become a major challenge in this field. To address the aforementioned issues, a solar-powered “methane co-reforming-high-temperature co-electrolysis” coupled system has been proposed. This system utilizes photothermal catalysis to simultaneously convert CH₄, CO₂, and H₂O into synthesis gas, while also producing high-temperature exhaust gas to provide a stable heat source and reactants for the downstream co-electrolysis unit, thereby synergistically achieving the electrolytic reduction of CO₂ and H₂O, forming an efficient carbon conversion pathway. For this system, a dual-module numerical model of thermal catalysis and electrocatalysis was constructed to systematically analyze its reaction performance and energy utilization efficiency under different conditions such as intake temperature, mole fraction, and feed ratio. The results show that the synergistic reforming system can increase methane conversion rates by 2.40% to 64.83% and solar-to-fuel efficiency by 2.70% to 53.92%. After introducing the co-electrolysis system, the electrolysis efficiency is significantly improved, reaching a maximum of 99.47%, an increase of nearly 30% compared to ambient temperature conditions. Increasing the CO₂ feed ratio further enhances the overall synergistic efficiency of the system. The thermo-electrochemical synergistic system constructed in this study not only effectively integrates the “heat source-water source-carbon source” chain, achieving hierarchical energy utilization and maximizing carbon resource conversion, but also provides a theoretical foundation and technical pathway for the construction of solar multi-energy integration utilization and green synthesis gas platforms.