Abstract: In order to solve the contradiction between operation distance and range resolution of the sonar, the principle of pulse compression is analyzed. The sidelobe suppression of linear frequency modulation signal (LFM) is introduced to avoid target omission. Considering the small product of timewidth and bandwidth of sonar system, the technique of modification to signal spectrum is adopted.The suggested algorithm is simulated by MATLAB and realized based on ADSP-BF506F in our experiment.