With the transportation sector a significant source of carbon emissions， its emission reduction effectiveness plays a critical role in achieving the “dual carbon” goals. This study adopts the shadow price method to estimate the carbon emission reduction costs of the transportation sector across 30 provinces in China from 2010 to 2020. On this basis， the carbon emission reduction potential of each province is evaluated from the perspectives of equity and efficiency， and the Spatial Durbin Model is used to analyze the factors influencing carbon emission reduction potential. The research findings are as follows：（1） From 2010 to 2020， the carbon emission reduction costs of China’s transportation sector exhibited an upward trend with fluctuations， characterized by higher costs in the western regions compared to the eastern regions. （2） Significant disparities exist in carbon emission reduction potential among provinces， with the eastern regions generally showing higher potential than the western regions. （3） The main factors influencing the carbon emission reduction potential include scientific and technological investment， transportation structure， economic development level， industrial structure and informatization level. Among them， the increase in scientific and technological expenditure is the key factor in reducing carbon emissions in the transportation industry. To effectively promote carbon reduction in the transportation sector， efforts should focus on reducing emission reduction costs， fully leveraging emission reduction potential， and deeply promoting regional collaborative emission reduction.