Nd-Fe-based rare earth transition compounds are composed of many different types, and most of the structures of the compounds can be converted into each other under certain conditions. The transition between the phases existing in the preparation of the rare earth permanent magnet material has a great influence on the magnetic properties of the permanent magnet material. However, the previous studies have less analysis of the phase transition process in Nd-Fe compounds. In this paper, NdFe₁₂ ingots were prepared and EDS spectra were used to analyze the phase transformation process in the ingot during cooling, and the melt quenching method was used. The NdFe₁₂ ribbon was prepared and the composition of the phase in the ribbon was analyzed by X-ray diffraction. It has been found that the phase composition in the ingot and the ribbon is affected by the cooling rate. Controlling the phase composition and phase transformation process of NdFe₁₂ compounds is of great significance for the preparation of NdFe₁₂N_x low rare earth new generation permanent magnet materials.