This article aims to identify the effective factors in the process of militarization of Caspian Sea. By militarization, Caspian policy entered a new round, a process which started from 2002. Until this year, the military power of the countries in the region was limited to a coast guard, but in 2002, because of the tensions over the legal regime of the Caspian Sea, especially after Russia’s naval maneuver, trends among the neighbors for establishing naval forces came to the life. Since that time, the amount of investments and initiatives for developing military power at Sea has been increased in these countries. In addition, western countries, especially America, has been influential in this process. Given the tendency of these countries to weaken the position of Russia and Iran in the region, through strengthening countries like Azerbaijan, Kazakhstan and Turkmenistan, Washington tried to give the necessary capital and equipment to these countries.Generally, the dispute over the legal status of Caspian Sea, regional competitions and ultimately, the competition between Russia and America are the most important effective variables to the militarization of Caspian Sea.