<p>Carbon emissions trading (CET) and renewable energy support policies are key mechanisms facilitating the low-carbon transition of China’s power sector, and will continue in the long-term. China is undergoing electricity market reform. In this context, evaluating its complex impacts on the power sector is essential for effective policy implementation and offers valuable insights for policymakers. Accordingly, this study employs a system dynamics framework to construct the causal relationships among these factors and establishes various policy combination scenarios to examine the long-term effects on China’s power sector, including electricity prices, carbon emissions, and the deployment pathways of different technologies. Results reveal that: (1) CET is the most effective mitigation mechanism, with the scenario featuring CET alone under market-based pricing achieving the lowest carbon emissions of 843 million tons in 2060. However, the effectiveness of CET is undermined by renewable energy support policies, leading to higher carbon emissions. (2) Renewable energy policies accelerate the deployment of wind and solar power, with feed-in tariffs exerting a stronger influence in the early stages, while renewable portfolio standards become more effective in the middle and later stages. (3) Market-based pricing mechanisms facilitate the phase-out of thermal power plants more effectively than benchmark pricing. When combined with CET, more deployment of CCS is observed. Under market-based mechanisms, electricity prices show an inverted “N” shape. These findings highlight the necessity of a well-balanced portfolio of CET and renewable energy support policies, contributing to lower policy implementation costs, enhanced renewable energy deployment, and further providing valuable policy insights for the long-term development of China’s power sector.</p>