The invention relates to a thermal-deformation magnet, a method and device for preparing the magnet and a rotating motor containing the magnet. The component of the magnet is RxFe100-x-y-zMyBz, wherein R is a mixture of Nd and one or more of Pr, Dy, Tb, Ho and Gd, M is one or more of Co, Ga, Al and Cu, wherein x is greater than or equal to 12.5at.% and is smaller than or equal to 15at.%, y is greater than or equal to 0.3 at.% and is smaller than or equal to 3at.%, and z is greater than or equal to 5at.% and smaller than or equal to 8at.%; the thermal-deformation magnet contains grain groups which comprise main-phase grains of R2(Fe, M)14B and grain boundary layers between the grains, and the standard deviation of the content of the rare earth in the grain boundary layers is higher than 10. The thermal-deformation magnet is ejected on a rotating roller wheel through a double-crucible and double-nozzle structure, and rapid quenching magnetic powder is prepared. Because the average rare earth content of each grain group of the magnet is uniform, the structure uniformity of the whole magnet is improved, and the overall property is improved.