In view of the fuzziness and uncertainty of the combat effectiveness evaluation index of small bore naval gun, combined with AHP and fuzzy evaluation method, the combat effectiveness evaluation method of small bore naval gun is studied. Firstly, the main influencing factors of the combat effectiveness of small bore naval gun are analyzed, and the index system of combat effectiveness evaluation is established. Then, based on AHP and fuzzy evaluation theory, a fuzzy evaluation model of small bore naval gun combat effectiveness is established. Finally, an example is given to evaluate the combat effectiveness of a small bore naval gun. This method can effectively unify the qualitative and quantitative indexes in the evaluation indexes, and provide an effective method and way for the combat effectiveness evaluation of small bore naval gun.