Abstarct: In today’s world, stock market companies play a crucial role in working capital and in its best allocation and they strive hard to use the capital, which is not working, in the sectors which generate the economy. One of the most important issues of the above-mentioned companies are competing with each other so as I attract the customers; to put it simply, to attract both potential and actual customers. That is why identifying the effective factors of customers’ faithfulness in competitive markets seems vital and it has a considerable impact on interest raise and having an enduring relationship with customers and consequently keeping up with the most significant goals of the companies. Therefore, identifying customer’s behavior will be considered important and one of the most noticeable challenges of today companies is knowing the customers, making a differentiation between different groups of customers and putting them into categories. So sorting out the customers and having enough information in customers’ loyalty and choosing appropriate marketing techniques would be of great importance. In an effort to achieve this goal, regarding the studies conducted in the field of sorting out the customers’ satisfaction, there has been presented a method baxsed on Rough Theory which can be used to predict a permanent pattern as a rule governing the customers’ behavior. It should be stated that measuring the amount of customers’ satisfaction in each cognitive factors in this study was received in a period of 3 months between 1.4.97 and 1,6,97 from Mofid Company. The obtained information was used in Rosseta software. According to the results of the study done by software, 6 obtained rules with a high reliability were achieved.