A method for mitigating interference at a small base station in a hierarchical cell structure is provided. In the method, the small base station checks a sub-frame allocated to macro user equipment by using a downlink signal received from a macro base station when an interference candidate user equipment list is received. The interference candidate user equipment list contains information on the macro user equipment adjacent to a femto cell controlled by the small base station. Then the small base station allocates other sub-frame to femto user equipment located in the femto cell by avoiding the sub-frame allocated to the macro user equipment.