To accurately figure out the stress and the deformation of the impeller, the one-way fluid-structure interaction was performed, utilizing the ANSYS Workbench. The pressure of the fluid flow and the centrifugal force imposed on the impeller respectively were used to evaluate the maximum equivalent stress and deformation of the impeller. Then the effect of two loads jointly imposed on the impeller was obtained. Based on these procedures, the stress and deformation behavior under different flow rates were numerically investigated. And the structural strength of the impeller was also checked. The results showed that the maximum equivalent stress and the deformation were primarily determined by the fluid flow pressure, and were less affected by the centrifugal force. With increasing flow rate, the maximum equivalent stress increased gradually and then decreased, while the deformation gradually decreased. The strength check result showed that the impeller could meet the strength requirement.