The aviation industry, contributing 2.8% of global carbon dioxide (CO2) emissions, faces significant decarbonization challenges. This study examines China's aviation sector, which is expected to become the world's largest market. An integrated model incorporating travel demand, fleet turnover, and technological improvements is developed to project future CO2 emissions. The results indicate that China's revenue passenger kilometers are expected to double by 2035, requiring an expansion to over 8,000 aircraft from 3645 in 2019, with 72% of the current fleet replaced, primarily by narrow-body aircraft. Improvements in technology and operations and the integration of Sustainable Aviation Fuel (SAF) are expected to enhance fleet carbon efficiency by 2.0% per year. These measures could reduce CO2 emissions by 290-460 Mt cumulatively by 2035, with advances in aircraft and engine technology accounting for 60%-70% of it. However, even under the lowest-carbon scenario, aviation emissions in 2035 will surpass 2019 levels by 50%, underscoring the challenge of capping emissions. Implementing the international Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) and current SAF mandates would impose a significant financial burden exceeding $10 billion for China (2025-2035). The study underscores the urgent need for effective decarbonization policies for aviation in China.