While in the political and legal regimes and doctrines, there is much emphasis on international agreements and conventions for international arms control and promoting peace, yet since the beginning of the third millennium the role of preventive diplomacy has become more important in this regard. The question raised by this paper is that" what are the achievements and role of preventive diplomacy in international arms control and what are the mechanism and solutions for promoting peace? " The underlying hypothesis is that the role of preventive diplomacy in international arms control can be evaluated in peace time, time of crisis and time of outbreak of armed conflicts. In peace time functions of preventive diplomacy are in the fields of confidence building, institution building and early warning, in the time of crisis, fact finding, crisis management and preventive deployment of force and in the time of armed conflicts, disarmament of both sides of conflicts and their destruction of weapons and economic recovery of the country or the region affected by war to prevent them reentering armed conflicts and increase use of weapons. The methodology used in this paper is descriptive-analytical and the necessary data have been collected on the basis of library sources.