This paper mainly focuses on an empirical study for performance analysis which is caused by customizing of ERP systems. To conduct this study, four companies are selected in Korea and China, two companies for each country. This paper actually considers four factors for performance analysis of ERP adoption such as financial performance, user satisfaction, competitiveness, and ERP systems adoption, and the analysis of utilization performance is based on nine factors in terms of customizing of ERP systems. As a result of the analyzed results, we conduct comparison analysis about ERP systems customizing of the companies in Korea and China and suggest how to optimally customize for successful ERP systems adoption and application.