The large-scale war in Ukraine affected not only its socio-economic condition, but also the development of European countries and their security system. The purpose of the article is to define post-war socialization and develop directions for building a new security system in Ukraine and Europe to overcome the consequences of the war. General scientific methods were used for the research: the method of analysis, synthesis, systematization and comparison. The article proposes directions for the post-war revival of Ukraine and new elements of the European security system. The practical recommendations of the article can be used by the government of Ukraine, as well as by European institutions in the post-war period.