The molten salt pump is generally underwater structure. Vertical motor of molten salt pump is fastened on the foundation of the motor. And it is directly driving the pump with the elastic coupling. The pump body, pump bracket, intermediate pipe, outlet pipe, pipe flanges, bolts are fixed on the bottom plate and installed in the container with the bolting. Pump’s axial force and pump’s radial force (including the generation of the water pressure in the pump operation, the impeller and the weight of the rotor, etc.) need one-way thrust ball bearings, single row radial ball bearings and sliding bearings to bear. Because of this, molten salt pump can safely work. Bearing needs lubricating oil to grease and sliding bearing uses molten salt to grease for itself. So the lowest level of molten salt must be higher than the minimum level of impeller center line.