The comprehensive evaluation index system of highway traffic modernization is established on the basis of the long-term plan for highway energy-saving of China. The AHP-Entropy method is expounded for quantifying the weight of evaluation index. In order to make up for the deficiencies of the present highway traffic modernization evaluation method, the multi-level extensible evaluation model is developed with the extension method as the core. Jiangxi Province is studied as an example, indicating that the new method is applicable to highway traffic modernization evaluation.