The structure integrity of the flywheel of a canned motor pump was analysed analytically and numerically by using finite element software ANSYS.The integrity analysis was concerned in the aspects of structure strength and fracture mechanics under the rated speed as well as the design speed.The analysis results show that the stress and the imaginary stress intensity factor are both satisfactory to the requirements of regulations and it can be concluded that the result is credible due to the consistency between the results of analytical method and finite element method.