This study developed a novel two-way dynamic coupled numerical model to simulate moving solids in free surface flows. The fluid flows and hydrodynamic pressures are simulated by a Large Eddy Simulation model, and the free surface is tracked by the Volume-of-Fluid (VOF) method. The fluid response from the solid motion is modeled through specifying the cell-face velocity with partial-cell treatment (PCT). The displacement and rotation of the solids are calculated by the Discrete Element Method (DEM). In order to verify the present model, two laboratory experiments of rectangular blocks floating and sinking in a water tank are conducted. The numerical simulations compare favorably with the experimental results on the trajectory of the moving blocks. The numerical scheme presented in this paper can be used as a design tool for practical problems involved moving objects in free-surface flows.