Abstract: Interacting multiple model(IMM) algorithm based on fuzzy logic inference is proposed,according to the requirements of real-time performance and reliability of the underwater maneuver target tracking as well as the features of the underwater target motion.Maneuvering patterns are represented by the model sets including constant velocity model,singer model and the nearly constant speed horizontal-turn model in simulation.The simulation results show that the reliability and real-time performance of the underwater mobile target tracking can be improved by the fuzzy IMM algorithm.