Negative externalities of transportation have long been a concern globally, and sustainable transportation is a shared goal among nations. Fuel taxes are regarded as an important economic means for transportation to curb fuel consumption, reduce traffic environmental pollution and realize green transportation. This study constructs a new index, Sustainable Development Efficiency (SDE), which integrates economic, environmental, and social sustainability using the Range Adjusted Measure (RAM) model of non-radial data envelopment analysis. Furthermore, the study employs the system Generalized Method of Moment (GMM) method to estimate the policy impact of diesel fuel tax on transportation SDE in China. The results indicate that a higher intensity of diesel fuel tax indirectly enhances transportation SDE in China by inhibiting the increase in truck ownership and operation in developed provinces regarding road freight transportation. Conversely, in less-developed provinces, the intensity of the diesel fuel tax can indirectly contribute to the increase in SDE by curbing the number of traffic accidents. Regional heterogeneity in SDE is evident: while western China shows potential for growth in road freight transport under the premise of ensuring environmental and social benefits, eastern China should speed up efforts to transform road freight transport into a more environmentally friendly and safer mode of transport.