Beginning from the analysis of the lack in CRM＇s （customer relationship management）, the importance that selling should operate based on the analysis of customer himself is emphasized, and the simplified state guide line is given. A CRM model is set based on this thought, the index, Pfeifer and Carraway＇ s model and Markov chain, then the corresponding computing result and their analysis are given for the case of one period and more periods selling in finite horizon, also the case in infinite horizon. Considering the practice, the model＇s result is discussed, based on the different selling policies. The result shows decreasing those sales with smaller success probabi lities will help the enterprise to get more profit