Abstract：The distinguishing index and grading standards of expansive soil are recommended by Specifications for Design of Highway Subgrades(JTG D30–2004). Its feasibility for expansive soils in the middle area of Anhui Province is discussed，and the correlation of three distinguishing indexes and consistence of classification grade are analyzed. The analytical results indicate that the standard absorption moisture possesses the better sort feature，but the classification grade is obviously higher according to the above specification，and the free swelling ratio of expansive soil in the middle area of Anhui Province is lower. On the foundation of above research，the grading standards for the expansive soil in the middle area of Anhui Province is suggested，and the classification result can achieve better unanimity according to the suggested standards. Finally，verification analysis is carried out by consulting the content of colloidal particle less than 0.002 mm and the content of montmorillonite. The analytical results illustrate that the suggested standards possess the better applicability for expansive soil in the middle area of Anhui Province.
