Multi-beam fishery sonar is an important tool for marine fish resources detection and spatial distribution analysis applying . hydroacoustic methods. This paper expounded the principle and working process of multi-beam fishery sonars. By analyzing underwater acoustics theories integrating with the application of multi-beam fishery sonars in marine fishing, this paper offered a range prediction model, and analyzed the main factors affecting the detection performance. Aiming at the omnidirectional detection of high sea purse seine and trawl fishing, this paper focused on the simulation and analysis of selection methods for the optimal operating frequency, and detection performance for cylindrical array multi-beam fishery sonars, revealing the constraint relationship among the maximum operating range, minimum size of transducer array and the best working frequency. The detection performance under the influence of noise and reverberation was evaluated respectively, the optimal operating frequency point to achieve the maximum detection distance under the given size of the transducer array and the optimal operating frequency point to achieve the minimum size of the transducer array under the setting of the maximum detection distance were both given. An optimal frequency selection method for multi-beam fishery sonars under certain deployment or application conditions was proposed, and the detection performance of fishery sonar was evaluated. It was proved that the diameter of the transducer applicable to the ocean fishing was 0.375 m, the maximum detection distance for the 0dB shoal was 2 600 m, and the optimal operating frequency best be 25kHz. The results will provide theoretical guidance for follow-up equipment development, testing and experimentation.