Supplier selection in a mass customization environment is a systematic engineering, and Quality Function Deployment (QFD) based on customer demand is a systematic product development method. This paper studies the adaptability of the QFD method and supplier selection process in a mass customization environment and puts forward a supplier selection framework based on the QFD idea. Furthermore, both the objective environment of demand factor analysis and the thinking of the customer representatives participating in the analysis have great uncertainty and fuzziness. Therefore, a demand factor analysis method for supplier selection in the mass customization environment based on language phrases of different granularity is proposed. The proposed method allows the customer representatives participating in the selection to use their preferred language phrase set to represent the importance of demand factors. Finally, the effectiveness and feasibility of the proposed method are verified by an example of a vehicle manufacturer.