Previous studies have focused on a lot of aspects of CRM (Customer Relationship Management). However, there is a severe lack of research that takes a focus on the relationship between competitive advantage and CRM, especially current CRM involving more and more data mining technology to enhance its function. CRM competence is very important source for enterprises to build and sustain competitive advantage. With the extensive application CRM, enterprises have accumulated plenty of customer data. DM (Data Mining), a useful technology extracting knowledge from complicated customer data, is helpful to identify customer demand accurately and promote customer value effectively. This paper explains how CRM competence can help enterprises gaining and sustaining competitive advantage from three different views, and discuses that DM is kernel function in CRM to help enterprises understand and insight their customers. The relationship between competitive advantage and CRM based on DM proposed by this paper is able to instruct management decision-making and help business enterprises obtaining and maintaining competitive advantage.