This contribution addresses the problem of expressing preferences among non-functional properties in a Web Service architecture. In such a context, semantic annotations are needed and added on service declaration and business process in order to select the best available service. These conditional and unconditional preferences are managed using Conditional Preference-Networks (CP-Nets). But in several cases, uncertainty related to the preferences has to be taken into account to achieve a better satisfaction rate. We propose the use of fuzzy linguistic information inside the whole process when it will be necessary.