In this study, the numerical analysis is carried out to study flow around moving body using unstructured overset grid. In order to investigate flow simulation, Navier-Stokes equation for incompressible flow is calculated with unstructured mesh. Unstructured mesh that is flexible to geometry. And overset method is applied to interpolate between cell data of each mesh in overlap region. This method advantage is to avoid remeshing for each different case and compute efficiently relative motion. The results of the present research can be used as basic data for more complex problem (e.g. 3D problem, ship propeller, etc)