Magnetic stability is an important indicator of permanent magnet materials, and the stability of the magnet directly affects the reliability of its operation. Magnetic materials, as important functional materials, have been widely used in key components such as aerospace and high-performance spacecraft. For magnetic components applied in space environments, good stability is required, including stability under temperature, impact vibration, strong electromagnetic field, and particle radiation conditions. Improving the stability of magnetic materials is an important task that requires high reliability, high precision, and high stability for magnetic devices used in aerospace systems and high-performance weapon systems. Among various factors that affect the stability of permanent magnet materials, temperature has the most significant impact on the stability of the material. Permanent magnets are generally used as magnetic field sources to provide a constant magnetic field within a certain air gap. Most magnets work in an open circuit state, and the magnetic induction intensity of the permanent magnet in the working state is not at the Br point in the closed circuit state, but at a certain point on the demagnetization curve lower than Br, which is the working point of the permanent magnet. The working point of a permanent magnet is related to the shape of the demagnetization curve and the magnitude of the demagnetization field HD of the magnet. Therefore, in the design of magnetic devices, the magnitude of the demagnetization field of the magnet in the working state needs to be carefully considered. NdFeB rare earth permanent magnets are highly sensitive to temperature, and the effect of temperature on magnetic properties has a certain size effect. The ability of magnets with different demagnetization fields to resist external magnetic field interference varies, and the thermal demagnetization behavior of magnets is also different. These characteristics cannot be ignored in the design of magnetic devices.