Abstract: In this paper, a passive acoustic fuse method is presented based on energy feature of target. Through analyzing the information of energy change as a target passes by the fuse, a method of seeking the optimum time for detonation is obtained. By considering the sound level differences of receiving signal to decide whether the target is passing by at a minimum distance, and then by making the decision whether the detonating signal should be output, the optimal detonating time can be sought. Experiment results show its rationality.