Nutation reducers have recently attracted increasing attention, as they are used in important components of industrial robot joints. A novel disk-type nutation magnetic drive (NMD), based on the nutation gearing principle, is proposed in this article. Subsequently, a 3-D method for analyzing the magnetic field and predicting the torque of the disk-type NMD is presented. The 3-D analytical formula of the disk-type NMD is established on the basis of the equivalent current theory of permanent magnet, which is verified by the finite-element approach. Optimization design of the disk-type NMD is also carried out by applying the genetic algorithm. The results provide a reference for the design and optimization of the magnetic gears.