Abstract: A customized ERP system is developed for small and medium-sized discrete manufacturing enterprises. The ERP system has a core of three layers BOM and eight main modules. Supply management module is highlighted in this paper. Parts are classified into 22 categories. Order management is applied in the module. Order number is connected to part number. Technical drawing can be loaded in database and displayed on interface as well. Industrial practice proves that customized ERP system is compact, practical, and friendly. It conforms to the enterprise's habit and can improve production efficiency. This study offers a good experience for small and medium-sized enterprises.