When decision makers are hesitant among different linguistic terms, the traditional use of one single linguistic term will restrict the accuracy of personal preference expressed by experts, it is necessary to use composite linguistic term which contains both the one single linguistic terms and the comparative linguistic expressions. Firstly, with the use of context-free grammars, two-tuple linguistic representation model and hesitant fuzzy linguistic term sets, the linguistic expressions of the preference relations provided by experts are transformed into judgment matrix, then the suitable aggregation operators will be selected to obtain a best solution to the problem. Finally, a new group decision making model based on composite linguistic expressions has been proposed and a practical example has been analyzed to verify the reasonability and feasibility of the approach.