<p>Besides industrial production, transportation-related activities constitute another major component in urban carbon emissions. Quite a few cities worldwide have effectively influenced travel mode choices and achieved favorable policy outcomes by implementing measures such as carbon taxes and other market-based policy tools. Shanghai also released its carbon peaking targets by 2025 and beyond. To evaluate the potential effectiveness of carbon taxes in adjusting residential travel behavior and reducing emissions in Shanghai, this study constructs a comprehensive policy portfolio with carbon tax at the core, to reduce carbon emissions by optimizing the structure of travel modes. Utilizing a mathematical model that incorporates variables such as carbon tax efforts and travel costs, we calculate the carbon emissions generated by urban resident travel and assess the effect of carbon tax policy on the adjustment of travel mode structures and corresponding carbon emission reduction effectiveness. Additionally, this study examines the optimal carbon tax range to determine its potential in realizing the carbon emission reduction targets for the transportation sector as outlined by the Shanghai Municipal Government. Results show that the carbon tax can effectively reduce travel carbon emissions, but when the carbon tax exceeds 18.138RMB yuan/kgCO₂, the total amount of carbon emissions from resident travel changes from a decrease to an increase. High carbon taxes may also drive people back to using private cars, necessitating Shanghai to develop more nuanced carbon tax policies, as indicated by our findings, to advance sustainable urban transportation and environmental conservation effectively.</p>