Numerical simulations for free surface flow models, which are water entry of several rigid bodies, fluid tank sloshing and flood disaster over several rigid bodies were conducted by using an Incompressible smoothed particle hydrodynamics (ISPH) method. The governing equations are discretized and solved with respect to Lagrangian moving particles filled within the mesh-free computational domain and the pressure was evaluated by solving pressure Poisson equation using a semi-implicit algorithm based on the projection scheme to ensure divergence free velocity field and density invariance condition. In this study, we modeled the structure as a rigid body motion by two different techniques. In the first technique, we modelled the rigid body corresponding to Koshizuka et Al. . They proposed a passively moving-solid model to describe the motion of rigid body in a fluid. Firstly, both of fluid and solid particles are solved with the same calculation procedures. Secondly, an additional procedure is applied to solid particles. In the second technique, we compute the motions of a rigid body by direct integration of fluid pressure at the position of each particle on the body surface and the equations of translational and rotational motions were integrated in time to update the position of the rigid body at each time step. The performance of these two techniques was validated through the comparison with experimental results.