The problem of consumers choosing smart phone is discussed in this paper. The influencing factors of purchasing smart phone are analyzed according to the Delphi method, and 11 evaluation indexes are initially established. Then, rough set attribute reduction principle is used to reduce the 11 evaluation indexes and the 6 core evaluation indexes are obtained. Finally, the entropy weight method is used to empower these evaluation indexes, and the comprehensive evaluation model of the smart phone is established. The selection of those 12 smart phones is evaluated. The results show that this method is effective and reasonable.