In order to investigate the effect of the splitter blades on the unsteady flow and structural dynamic characteristics on the molten salt centrifugal pump, the directly coupled method, considering the interaction of fluid and structural fields, was applied to compare the unsteadiness and structural dynamic characteristics of the pump with and without splitter blades by using the ANSYS CFX 12.1 and ANSYS Workbench. By comparing the results of the unsteady flow and the structural characteristics, some conclusion are drawn: the results of pressure fluctuation and the radical trust are changed greatly, which indicate that the effect of FSI is quite obvious which cannot be ignored; the pressure fluctuation, the radical trust, the maximum equivalent stress fluctuations, the maximum deformation fluctuations, and the equivalent stress distribution and deformation of the pump are decreasing by adding splitter blades, which can prove that the splitter blades can improve the impeller blade loads and the capability of anti-fatigue.