The financial situation of the Ukrainian pension system and the problems of its reforming play an important role in determining the general standard of living in the country. The institutional weaknesses in the financial management of the state pension system have led to an unbalanced budget of the Pension Fund of Ukraine and a low standard of living for pensioners. In order to identify the potential for building an effective system of pension insurance, it is necessary to study the modern aspects of financial provision of the Ukrainian pension system. The article defines the economic interrelations between the processes of forming the financial resources of the Pension Fund of Ukraine and the volume and structure of the gross domestic product. In view of this, the financial sustainability of the state pension system of Ukraine has been researched and the determinants of its stable functioning in the years 1999–2017 have been identified, which enables to influence the process of effective formation and use of pension resources and to identify the strategic directions of reforming the pension system.