Abstract: Based on the benchmark submarine model, the structural characteristics of highlight echoes of single and double shell submarines in the torpedo homing frequency range are studied with planar elements method. The difference of highlights at different frequencies is compared, and the influence of sound absorption material on the highlight echo is analyzed. The results show that the difference of highlight echoes between double shell and single shell submarines is reflected at the angles nearby bow and stern, while the difference in the vicinity of abeam is very little. The anechoic coating has great inhibitory effect on the highlight echo, but the highlight coming from the internal structures is also obvious as frequency decreasing.