Abstract: Based on the planar element method and the physical acoustic method, the target strength and echo-to-reverberation ratio of bottom mines which are modeled by the geometric drawing software are calculated A certain bottom mine is taken as the example. The target strengths of the mine are compared at free space, on the silt bottom and on the clay bottom. This paper discuses the influence of the send-receive beam width on the target strength of the bottom mine and contrasts the echo-to-reverberation of the bottom mine at different field angles, pitch angles and position angles. The results show that it is effective to detect bottom mines in some areas.