The ethnic crises of the first decade of the Islamic Revolution caused many effects on the national security of the Islamic Republic of Iran. The main question has been raised as follows: What effect did separatist movements have on the national security of the Islamic Republic of Iran in the first decade of the Islamic Revolution? In response to this hypothesis, it has been proposed that separatist movements in the first decade of the Islamic Revolution have become the basis for weakening the national security of the Islamic Republic of Iran. The findings of the article show that, in general, in the first decade of the Islamic Revolution, the existence of various crises in various dimensions contributed to endangering the national security of the Islamic Republic of Iran. In the meantime, the presence of separatist groups in Kurdistan, Sistan and Baluchistan, Gonbad, etc. caused the weakening of economic, political, military, etc. security. On the other hand, since the Islamic Republic of Iran was involved in the war with Iraq and also had recently established an Islamic Republic government with the overthrow of the Pahlavi government, the existence of separatist movements is more effective in jeopardizing the national security of the Islamic Republic of Iran. was The current research method is descriptive-analytical. Also, in order to theoretically support this research, national security theories have been used.