Considering measurable evidence and fuzzy measures that involve linguistic terms, this thesis proposes a fuzzy-number based Choquet integral to aggregate linguistic information when information fusion between criteria is considered. The proposed fuzzy-number based Choquet integral is a generalization of a standard Choquet integral that can cope with interval-number or fuzzy-number types of measurable evidence and fuzzy measures. Furthermore, by investigating the related characteristics of the Choquet integral and the fuzzy-number based Choquet integral, the operation process of the fuzzy-number based Choquet integral is clarified in this thesis. Combining linguistic terms and the compatibility of psychology, fuzzy numbers and the fuzzy-number based Choquet integral, when information fusion between criteria is considered, are introduced into evaluating service quality and aggregating information in three-column format of SERVQUAL. Finally, a numerical example, regarding the comparison of overall service performance between e-stores, is demonstrated to illustrate how the fuzzy-number based Choquet integral and its two-stage aggregation process operate in three-column format of SERVQUAL for evaluating service quality.