In order to achieve the integration of a supply chain with upstream and downstream manufacturers that are cross-border and cross-regional, Enterprise information systems, such as Enterprise Resource Planning (ERP) systems, have been applied to organization-wide coordination and the integration of business functions and processes. But these information systems are usually a platform for data exchanges, lacking the function of decision-making that is required in cross-border operations and planning scenarios. ERP-based Decision Support Systems (DSS) have been developed in some industries, but there are few studies of application cases. In this research, on the basis of ERP, we study the advanced planning system (APS) with theory of constraints (TOC) in decision logic design, and the system development of a master plan in a flat-panel display systems manufacturer. The results show that the case company, establishing a new system with the methods proposed in this paper, enhances planning and decision-making speed faster than the old one. The inventory level of final products and shortages of Vendor Managed Inventory (VMI) hubs are improved. This successful case offers a reference to other enterprises.