Abstract: new index, the air-dry moisture content W65, is recommended in the defect of free swelling ratio ef in the identification and classification of the swelling soil. The weasurement method of the index. its relationship to the physicochemical activities. moisture index and free swell ef of the swelling soil are also studied in this paper. The results indicate that the W65 can be better than ef or WL to reflect properties and composition or physicochemical activities of the swelling soil, and ef orWL is better than W65 to reflect property of the size composition or dispcrsity. Finally, on the basis of the results of identification and classification of ef, in consideration of the advantage of the plasticity chart adopted,a new mcthod of W65-WL chart is recommended for identifying and classifying the swelling soil. it is applicable to identify swelling soil and red clay, and is more reasonable and applicable than ef.