Abstract: The electromagnetic CT is widely used in the Karst exploration. The statistical analysis of the Karst which developed in T₁d, combining with drilling data, has been done in this paper. The apparent absorption coefficient of the Karst in this stratum has been determined, which is being used in the interpretation of the electromagnetic CT and being verified by the verification hole. The important issue of anomaly identification in electromagnetic CT has been solved in this study, which is able to provide important guidance for Karst exploration of T₁d in Wuhan.