The power transfer capability has been recently highlighted as a key issue in many utilities. The total transfer capability in the KEPCO power system is determined mainly by the voltage stability limit and an enormous number of contingencies should be analyzed to determine the total transfer capability. In this paper, a new ranking index for determining the total transfer capability from voltage stability point of view is presented. This index is applied to the practical system of KEPCO and the effects of ranking the contingencies are analyzed by use of PSS/E package and a developed IPLAN program.