Abstract: Nuclear Hot Spring is a novel design concept of molten salt pebble-bed reactor, featured by the full power natural circulation, with the primary coolant flowing radially through the reactor core. By using CFD software Fluent, the thermal-hydraulics of the radial flow reactor core of the NHS were obtained based on the local thermal non-equilibrium（LTNE） porous media model. Different opening ratios of the central and outer perforated plate were simulated. The simulation results indicated that the opening ratio of the central perforated plate has a great effect on the flow field distribution of the coolant; the maximum pebble center temperatures are far below the safety limit of the fuel, the core resistance is considerably less than the buoyant force, indicating that the natural circulation under full power operation is possible.