The article reveals the mechanisms of the maintenance of international peace and security: preventive diplomacy, peacemaking, peacekeeping, post-conflict peacebuilding. Of peacekeeping operations carried out by a special unit – Department of peacekeeping operations. The article reveals the essence of the mission of UN peacekeepers and provided official information of the UN on the subject. There are three main stage of peacekeeping and corresponding stages of the various measures and specific activities. Pre-conflict peacemaking is implemented through General measures of conflict prevention, preventive measures in the format of sanctions, preemptive military action, preventive humanitarian action. The peacemaking stage of conflict is implemented through the measures of localization of the conflict, the measures for the protection and conservation of different groups of persons and objects, military force to end the conflict. Post-conflict peacebuilding is implemented through measures to prevent the recurrence of conflict and measures for the restoration of civilian infrastructure. Peacemaking is realized in the form of individual peace operations, contents and settings which may be different. The article expresses the view that the most important criteria of differentiation of peacekeeping operations are: the purpose of the entity, “issued” mandate, functions and composition of the personnel engaged. It is noted that in the framework of international peacekeeping is to encourage the conclusion of agreements between the parties for the purposes of post-conflict development of peaceful relations, and specifies that the guarantors executing such agreements must be, first of all, international organizations. These are the types of activities that are essentially of the measures taken are similar to international peacemaking, but formally are not.