In the estimation of fish target strength, it is necessary to select the single echo signal for calculation. The phase standard deviation of the echo in a narrowband signal is a key indicator of the single target detection, but the phase difference between two adjacent points of a wideband signal is time-varying, so the phase standard deviation of the echo can’t be used as the judgment basis of single signal. This study analyzes and simulates the method and performance of single target recognition under LFM wideband signals, then tests and validates the method in an anechoic pool. The result shows that compared with narrowband signals, the range resolution of the wideband signal is directly proportional to its bandwidth. With the increase of bandwidth, the range resolution of wideband signal detection increases, and it has a better single target recognition performance. Compared with the single signal echo, the short-term angle change in a multi-target interference echo with a close distance increases significantly. Using the standard deviation of the internal angle of the echo as the single target recognition parameter instead of the phase standard deviation can also obtain good recognition performance.