Abstract: Computation of bi-static target strength(TS) of elastic objects using the Finite Difference Time Domain (FDTD) Method and separation of forward-scattering sounds from interferential signals between the direct and target scattering sounds were researched.3D scatter sound field of elastic cylinder with flat cap,spherical cap,spherical-core cap,and prolate spheroid was calculated using FDTD,then near-far field translation used to get the TS of far field.The result of simulation shows distributing in space of TS influenced by incidence direct,kL(k-wave number,L-character size of target),shape,and material of target.Within the range of kL and the size of the objects with different shape in this paper,bi-static TS performs a prominent forward-scattering and enantiomorph-reflecting character.The numerical value simulation results are validated by comparing with analytic and experimental results.The signal correlation processing technology is used to separate the forward-scattering sounds from interferential signals between the direct and the target scattering sounds.The method is a simple and valid one to separation of forward-scattering sounds,which successful in this paper for separating the forward-scattering sounds of the target.