Pavement performance evaluation is a reasonable safeguard for the conservation plan and an important basis for investment decisions. In order to obtain a precise and quantitative evaluation result, a general evaluation model based on Extension Theory is established, and a concrete index is raised to indicate the pavement real condition. Practical pavement detection data of Jing-hu highway in Jiangsu Province is used to validate this model. The result shows that the evaluation model based on Extension Theory gives an accurate evaluation on pavement performance, and reflects the pavement condition well. It could provide solid foundation for pavement maintenance orders, and may have a bright future.