Requirements prioritization is recognized as a critical but often neglected activity during software development process. To achieve a high quality software system, quality attribute requirements must be taken into consideration during the prioritization process. However, prioritizing quality attributes is not an easy task due to the inherent interrelationships between these attributes. Although some methods on prioritizing requirements have been introduced in recent years, no particular method or technique is proposed for prioritizing system quality attributes. In this paper, an approach is presented in which prioritization of system quality attributes could be performed. Indeed, it provides the requirements engineering team with a set of ordered quality attributes which are prioritized based on their relative importance, take into consideration their consistencies.