Abstract: Permanent magnets are essential components of sputter ion pumps. Numerical simulation is used to analyze the spatial magnetic field distribution in the existing structure of sputter ion pumps, thereby obtaining the characteristics of the external and internal magnetic field distribution of the sputter ion pumps. Besides that, a double-layer magnetic shielding structure to reduce magnetic field leakage and an NN-pole co-directional array permanent magnet model to improve the uniformity of the internal magnetic field have been proposed. The double-layer magnetic shielding can provide more efficient shielding, and when the air gap ratio is controlled at 5%, the shielding effect can reach more than 80% of the maximum value; changing the single permanent magnet to an NN-pole co-directional array pattern can effectively improve the uniformity of the magnetic field. The proposed structural models offer a theoretical framework for optimizing the magnetic field design in sputter ion pumps.