The application of data mining in CRM (Customer Relationship Management) is a hot spot in recent years. CRM refers to the enterprise's approach to understand and influence customer behavior through meaningful communications in order to improve customer acquisition, customer retention, customer loyalty, and customer profitability. Adopting different services to different customers is based on the accumulation of vast amounts of data by the enterprise. The effective way to get the knowledge from these data is the technology of DM (Data Mining), which will provide basis for leader's decision-making, and achieve the objectives of CRM. The basic theory of the customer relationship management and data mining technology, and the application of DM in petrochemical enterprise CRM were discussed.