To address the problem of uneven cathode magnetic field distribution on the target surface during the coating process of existing magnetron sputtering devices, a new type of rotating cathode magnetic field device is designed. The device drives the magnetic field through a rotating mechanism, and the cam mechanism is used to make the magnetic field to move up and down in a straight line. Firstly, a threedimensional model of the device is drawn using 3D software. Secondly, a finite element analysis of the magnetic induction intensity of the cathode magnetic field is performed. Finally, the magnetic field is optimized by adjusting the height of the yoke, the length of the extended arm, and the distance between the yoke and the target material, and the numerical simulation curves before and after optimization are compared and analyzed. The results show that the uniformity of the magnetic induction intensity curve of the cathode magnetic field is improved from 21% to 6% after optimization, which effectively improves the uniformity of the magnetic field on the target surface, and beneficial to ensure stable operation of magnetron sputtering.