FSI(Fluid-Structure Interaction) is used to perform the the structural mechanical characteristics on the full tubular and the axial-flow pumps. The results show that as the flow rate increases, the total deformation and equivalent stress are significantly reduced. The MTD(max total deformation) and the MES(max equivalent stress) of the full tubular pump impeller appear at the outer edge of the blade. There are two stress concentrations in the full tubular pump impeller, in which one is located in the outlet area of the rim, and the other is located in the outlet area of the hub. However, the MES of the axial-flow pump appears at the center of the blade hub. The performance difference between the full tubular pump and the axial-flow pump is mainly caused by the clearance backflow. The natural frequency of the full tubular pump is lower than that of the axial-flow pump according to the modal results. The MES of the full tubular pump is mainly concentrated at the junction of the blade and the motor rotor, and the max thickness of the rim is 6mm, which is more prone to cracks, seriously affecting the safety and stability of the pump.