Based on the research of security and reliability of canned-motor pump at home and abroad in the design, manufacture, installation and the two-dimensional harmonic analysis of shielding the motor inside the main reactor coolant pump magnetic field, the distribution of the magnetic field inside the motor is revealed. through three-dimensional harmonic analysis of end of the main magnetic field in the canned reactor coolant pump, the distribution of the end of the magnetic field and the distribution of shielding sleeve of magnetic induction, the current density, electromagnetic force along the motor axis. Based on the analysis of above factors affecting the integrity of the shielding cover, the potential failure mode of can is studied. By shielding the main reactor coolant pump electrical stress analysis within the shielding sleeve, and compared with the allowable stress check, it comes that loads generated in the motor shield put less stress shielding sleeve material yield strength, can be set to ensure shielding integrity.