In the thermomagnetism analysis, the ferromagnetic amorphous alloy near or after the Curie temperature within a certain scope was in the paramagnetic condition with low magnetization. When the heating temperature achieved the crystallization temperature of the amorphous alloy, the magnetization increased significantly due to the crystallization of the alloy. As the obvious crystallization of the amorphous alloy, the crystallization phase with a high Curie temperature (Tc) formed and the ferromagnetism of the alloy would not be fully transferred to paramagnetism. The magnetization of the alloy would maintain at a stable high level before it had been fully crystallized. Therefore, the structure of the ferromagnetic amorphous alloy can be identified accurately by the obvious difference between the thermomagnetism curves before and after crystallization.