Disclosed is a method for preparing a carbide-derived carbon-based anode active material. The method includes preparing carbide-derived carbon, and expanding pores of the carbide-derived carbon. Here, expanding of pores is performed as an activation process of heating the prepared carbide-derived carbon in the air. The pores formed inside the carbide-derived carbon can be expanded during the activation process in the preparation of the carbide-derived carbon-based anode active material. In addition, by applying the carbide-derived carbon to an anode active material, lithium secondary battery having improved charge-discharge efficiency can be prepared.