A case-based method is important activity for variety system modeling in system architecture. The project planning management method and work breakdown structure is a reason why cost is wasted and a number of project planning is failed. It is necessary to develop a structure of work breakdown structure identification and output selection along to project's planning specificity in project planning management by case-based method. This study presents the method with the limits of the existing study that has uniformly been customizing the method in system architecture. And also present method to cope with the limitations of existing study that has uniformly customizing the method by case-based method in system architecture.