Abstarct: Abstract In recent decades, the development of the global network has provided users with various and new facilities. E-commerce and online business is one of the best features that have been provided for virtual sales. Customers of online stores do not decide to buy a specific product by accident; rather, a set of factors are involved in their decision making. The purpose of this research is to provide a related rule that shows the relationship between the effective factors in virtual sales and customer loyalty. The value of each criterion has been measured by the fuzzy quality control chart (spc) and the level of customer loyalty with net promoter score (NPS). The statistical population of this research includes the customers of 6 online food stores in areas 6, 7 and 11 of Tehran. These rules are extracted by Rought set theory and Rosetta software. According to the extracted patterns, the results show that quality and service standards are important for customers' virtual shopping