Abstract: According to the date of exploration and test in west anchoring tunnel at Balinghe River suspension bridge, the properties of weak intercalation in carbonate rocks are discussed in this paper. The research have proved that the genesis of this kind of clay and intercalation is a solution- replacement products in carbonate rocks. The physical and mechanical testing shows that the grain size analysis of intercalation is belong to the size of red clay, the shear strength of intercalation is similar with the strength of recent red clay and is also similar with other kinds of intercalation.