The detection performance of wideband split beam fish finder is the most important technical index, which directly affects the use of the fish finder. The detection performance is affected by various factors. In order to guide the subsequent development and use of this type of fish finder, it is necessary to sort out the influence process of different factors on its detection performanc. Using the modeling method of hydroacoustic system,  combined with typical parameters and marine environment, the effective rang prediction model and main restricting factors under noise background, volume reverberation background and volume reverberation and noise aliasing background are given according to the active sonar equation. The detection performance is simulated under different backgrounds. The influence of frequency on the detection performance of different target strength fishes under different sea conditions is discussed and the ability of narrowband systems and wideband systems to counter reverberation is compared. The effects of different parameters on the detection performance in the actual application environment are analyzed based on the simulation results, which provide an improvement direction for the development of long-distance, high-resolution wideband split beam fish finder.