By comparing the slope of self convertion of spin, it is discovered that the ferromgnetism crystal system has three kinds of possibilities of the thermodynamic state.

• 对铁磁晶体自旋自洽条件用斜率比较法分析发现,整个铁磁晶体系统无论有无外场的作用,只有三种可能的热力学状态。