This paper presents an algorithm that can calculate the evaluation index of power system from the transfer capability point of view. The algorithm adopts a successive linear programming skill to solve an optimal solution. Two indices which are transfer margin index and economic matching index have been developed. Prior to calculating these indices, Maximum Load supplying Capability(MLSC) and Economic Load Supplying Capability(ELSC) are utilized as basic data. For man-machine interface, graphical user interface has been implemented so that an unified software package PSTCP(Power System Transfer Capability Program) has been developed. KEPCO systems planned up to 2006 year have been tested to show effectiveness and usefulness of the PSTCP for power system planning stages.