Aimed at the operational effectiveness evaluation of navel gun weapon system, an index architecture was built with a fully consideration of related factors for navel gun weapon system. Then, the weight distribution of index architecture was estimated using the AHP method, and the operational effectiveness of weapon system was evaluated by the approach of fuzzy comprehensive evaluation. Finally, the model of effectiveness evaluation was applied to a case of lager-caliber navel gun weapon, which confirmed the validity of evalution model and pointed the technically weak factors of this weapon system. It could be concluded that this model of operational effectiveness evaluation could hopefully provide valuable advices on the future development and operation of navel gun weapon system.