abstract u.s. attack to afghanistan after 9/11 provided opportunities for us who tried to become the dominant power after collapse of ussr and bipolar world. thinkers like fukuyama believed american liberal democrats thought would be universally accepted without resistances. liberal democracy is the best and final model of governance; in this regard, united state has moral responsibilities for providing it. while, u.s. announced that its goals in afghanistan is moral policy. this country pursues some other security and strategic goals that are related to terrorism, opium, control irresponsible state including russia, china and iran as challenger players in the region. this development led to new geopolitics of afghanistan. new geopolitics of afghanistan`s elements including u.s. and nato presence, increased poppy production, failed state, developing islamic radicalism, and not completely suppression of taliban’s forces, avoiding afghan mujahidins forces and taking the power from pro-western afghans. iran a neighbor of afghanistan and has common historical and cultural heritage with this country. therefore, afghanistan development is important for iran. in this dissertation we study the new geopolitics of afghanistan after 11 september 2001 and its impact on iranian national security in short and long terms