Abstract: In order to improve the radiation effect of radiator in the high temperature molten-salt pump, the diameter and number of the radiating holes which are the significant factors to the radiation area were optimized numerically. The thermal load derived from the numerical simulation was loaded into the structure and the thermal deformation was analyzed. The results show that when the diameter and number of the radiating holes are 12 mm and 6 respectively, the flow of cooling fluid is uniform and stable. The pump shaft and radiator have a good radiation effect. The average temperature of the top of the pump shaft reduces to 440 K while that of the radiator decreases to 417.5 K. Thermal deformation of the pump shaft is small, and its maximum value is 0.46 mm. There is a larger effect to the radiator with the maximum deformation of 2.37 mm. Thermal expansion and thermal deformation of the material must be taken into consideration in the manufacture process.