Custom-oriented product design is the trend of cabinet electromechanical product. At present, the enterprise mainly used configuration design in product design. There are many insufficiencies in the process of cabinet electromechanical product customization design. Such as prompt delivery, success rate once and for all, cost and level of standardization. For enhance the level of customization design by utilizing knowledge reuse, the structure characteristics and the design method of cabinet electromechanical product was analyzed. Some critical problems was discussed based on configuration design patterns, including product structural, configuration design Knowledge ontology and reasoning method of knowledge reuse etc. Finally, a switchgear design case was illustrated.