As a serious threat to national security, especially the core security of one country, secessionism not only endangers the integrity of a country’s territory, sovereignty, and national identity, but also directly threatens national military security when violent methods are applied by the separatists and when outside interferences exist. Secessionism is a traditional security problems instead of a non-traditional security one.  China is facing a serious threat of secessionism. It would be dangerous to explain China’s core security interests by simply applying western theories.