The navigation of ships in sea ice is affected by the resistance of the ice-water environment, which is an important factor in the research of the power/speed of ice ships. The ship sailing in ice areas has been simulated by a fluid-structure interaction model based on the discrete element method (DEM) and smoothed particle hydrodynamics (SPH) method, to reasonably analyze the power/speed performance of ice ships. It obtains the resistance of the ship at different speeds, and the thrust and torque of the propeller, as well as the speed of revolution required for navigation at constant speed. A DEM-SPH model for the coupling of the hull structure, sea ice and seawater is established by directly calculating the interaction force between the structure and the fluid through the fitting of the relative motion between the SPH particles and the fixed particle boundaries, in order to study the fluid structure interaction between the hull structure, sea ice and seawater. Then the DEM-SPH coupling model is used to simulate the resistance and propulsion of the ships in ice regions. The resistance and thrust of the ships are matched through the fitting method with consideration of the influence of the resistance increment caused by the wake field, to predict the speed of revolution required for the self-propelled ship at a specific speed. The resistances of the DTMB 5415 ship model in ice floes and level ice and the propeller thrusts at different speeds of revolution are also simulated to predict the speed of revolution required for the ship sailing at specific speeds under different operation conditions. The results show that the fluid-structure interaction between the ship-ice and propeller-ice can be well simulated by the DEM-SPH coupling model, fully describing the drag effect of the ship hull and the wake field on the sea ice. A numerical simulation-based prediction of the speed of revolution for the self-propelled ship is performed through the simulations of resistance and thrust, and the fitting analysis of the forced force. It can provide foundation for further experimental verification and engineering applications.