Aiming at the problem of difficult to long-distance detect object in underwater condition, study on its scattering characteristic of object low frequency, using simulations mathematical method of acoustic scattering at low frequency based on of singularity–integral processing technique. Through simulating, we calculated echo strength which is under circumstances of different azimuths, positions of receiver and acoustic impedance. At the same time, we plot direction diagram of acoustic scattering at different wave number radii. The results demonstrate that the proposed new method can be used to the research of bistatic sonar and the scattering characteristics of complicated objects at low frequencies.